Same here.
We have 2 iPhones with iOS 7 at home. Both of our phones are set to Hungarian regional format. We've got Canadian holidays, and Hong Kong holidays on the other phone as a gift from the thoughtful Apple inc., which you can't delete, only "don't show", and it's turned on by default.
I really just can't understand the reasons why they have to dumb things down this much. I mean I get that they should create a "smart-phone" OS, but there is a certain level of customization that is in need to make it serve _you_ right! But it seems that they only think through "what they would need" in the Headquarters. Thanks, you innovating square-heads!
I mean they could have made a "holiday calendars" list under "settings > general > international" which you can !multiple! select from. And because its smart, it doesn't even should dare to try to assume that you want to see holidays from the way you want to display a date or time!
They should have think of real life people! for example: I want to see my iOS language in US English, my keyboard and regional settings in Hungarian since that is the way I was raised on and I need Monday displayed as "Hétfő" to feel my phone my own, and so on! But what if I decide to live abroad!? What i really will need then is that country's holidays to know when should I go to work or not!
I mean I know this is not the common situation, but it isn't a case that should be dismissed by a Calendar! Because this is a good example why I would need a calendar since I don't really need calendar for my own national holidays, i know them by heart.
Ok, I can add additional calendars, so its there... but I have to do it manually, or paste in an ".ics" URL...!! Really?? Yeah, that's smart... OK. Don't give me a list, which i can multiple "tick-in".... Give me Canadian holidays, because my dates are displayed in a format of YY/MM/DD (Hungarian)... Thank you Apple!