I have the heliport in my game and they don't have helicopters flying. It's just the way the game is designed. It could obviously do with being stated somewhere that you don't get helicopters around your city, or having it redesigned so you do.
Talked with support today and to them it's supposed to have heli's flying around cause it does not make sense to have airships and ballons fly around from the parks and you can see the firetrucks and police on the streets. Here is what they sent me in which they really don't even bother with my heliport question another weak point...
Hi Mayor,
Thanks for getting in touch! We do have a couple of flying animations in the game - it's possible to see Airships and Hot air Balloons floating around. You will see them flying around on your city limits, and we have some great plans for other flying vehicles in the future too!
It can take a little while for them to appear once your Transport service building has been built, but they'll be there. Keep an eye out at the edges of your city to have the best chance of seeing them. You might be able to spot them when you visit Mayor Daniel too.
Please let me know if there's anything else I can help you with. Thanks!
http://help.ea.com/en/simcity/simcity-buildit/
