1) All one needs to do is web search on union corruption to see the 'why'.
Please let's stick to FACTS, OK?
Unions are groups of humans, and sometimes a few humans act corruptly. Store and corporate managers are also fully capable of acting corruptly, and sometimes they do. There's an important difference, though: if a union leader acts corruptly then the members themselves (without any permission from their employer) can remove her/him and choose their new leader. If your manager (or some other manager in the chain) acts corruptly you don't have that right. You're also free to use your favorite search engine to look for "corrupt manager" and see what you get. Have fun.
2) No one should be forced to join a union and pay dues to be employed. Right to work FTW! If you like the idea of unions, pay your dues, if you don't, don't.
You aren't ever forced to join a union in the United States. That's been illegal since 1947 as many posters upthread have pointed out. You can join or leave the union whenever you wish. In many states you may be required to pay partial dues for the common, legitimate employment-related services that the union provides (on a pro-rata actual cost basis). Your total net compensation will still be materially higher than otherwise (almost certainly). And of course slavery isn't legal, so you can always choose whether to work for a particular employer or not.
3) Unions also tend to support only one political party leaving some percentage of members paying to support a party they don't want to support.
Unions may engage in certain permitted political activities, but they don't support only one political party. (Maybe/probably unfortunately.) You're never required to pay for a union's political activities (if there are any). That's illegal, too. So far there's only one Apple Store in the U.S. with a new union, and it has not spent even one penny on external political activities to my knowledge.
Apple (the corporation) engages in many political activities and spends millions of dollars each year in that way. As a rank and file Apple employee you have no influence over Apple's political spending. Apple may (and probably does) support many politicians and political causes that you disagree with. If many more Apple employees unionize then employees may have some actual input into Apple's political spending decisions.
4) Seniority based system for preferred shifts and overtime. How about a skill/performance based system?
Union and non-union employers offer seniority-based systems, and union and non-union employers offer performance-based systems. The only difference is that with a union the members have much more say in which system (or hybrid system) there ought to be. If you want more power (note: not anywhere near infinite power) to choose the type of system then you want a union.
5) Look at any major democrat run city and see how the city is overburdened by retirement benefits awarded to unions instead of salary increases. Kicking the can down the road at its finest. Then when the cities increase taxes to pay for these Cadillac retirement programs the people of that city freak out and leave.... in droves.
I have literally no idea what this observation (if it's even partially correct) has to do with whether Apple Store employees choose to unionize or not. Apple Stores are not municipal governments with taxation powers. Although some people talk about the "Apple Tax." (Joke.)
6) General thuggery when construction contracts are won by non-union companies. Web search 'scabby the union rat' and how those construction sites suffer 'unfortunate acts of vandalism'.
Same as #5. This is a non sequitur.
Do you honestly think unionized Apple Store employees are going to (I don't know...) throw staplers at Staples store windows? Of course they won't, but if anyone ever did that you should just do something else, like stay at home and watch a football game. And/or contact the police to report a crime if you see one.
Vandalism is a crime and ought to be prosecuted. And it's easier than ever to catch vandals at construction and other sites thanks to inexpensive closed circuit television recording and...iPhone cameras. This isn't the 1950s any more, and even that was overblown.
7) No ability to negotiate for yourself, you get what the union has negotiated.
Again, not true. There will be nothing stopping you from starting as a union represented Apple Store employee and becoming Tim Cook's successor if that's where your talents and efforts take you. The only material difference is you'll almost always have better total compensation (and working conditions) with union representation, so you'll be in better condition once you do take over for Tim Cook.
8) Protection of problematic employees. I have personally seen union employees protected even though they were caught stealing, sleeping, masturbating and sexually harassing other employees. In one instance, the sexual harassment one, the employee was fired but filed a grievance and won, was brought back after a year, seniority intact, back pay, etc. No consequences at all even though 10 people all saw and heard the harassment.
And I've seen non-union employees protected despite their horrible behaviors. (See #1.) The difference with union representation is that you have the option (not obligation) to ask the union to defend you when there's a dispute, and the union may or may not represent you. (That Internet search engine you like? Look for "my union won't represent me.") Another difference: many unions
help to remove bad employees. (Yes, seriously.) No union, no such efforts. If for example there's a jerk sexually harassing women and 58% of the union membership is women then that jerk isn't going to last very long. The union is most probably going to represent the jerk's
victims and help them convince the employer to fire the jerk. (This is particularly true if the jerk happens to be the owner's nephew, as an example.)
You're basically arguing that criminal defendants without defense lawyers, including innocent criminal defendants, are more likely to end up in prison. Yes, that's undoubtedly true. That doesn't mean criminal defendants shouldn't have competent legal representation. They should! The union members decide what sort of representation there ought to be (if any) in disputes.
You're perfectly free not to seek any help from the union if/when there's a dispute with your employer. Indeed, you may not even be a member of the union. (That's your choice, too, as noted above.)
Union membership in the United States is near an all-time low, but it might be starting to increase. I don't see any problem with union expansion in the United States and a lot to like. There's absolutely no danger that you'll be prevented from finding lots of jobs without union representation if that's your preference. Heck, right now there's only one Apple Store in the United States where you can work with union representation. Only one! So there's a real danger that you won't be able to find a unionized job. For a while at least it'd be better to see some union expansion to provide more and better choices to workers. Let them compete fairly and see what happens. If unions are as terrible as you think they are then that'll be self-correcting in the huge U.S. labor market.