If I'd never had ice cream from an ice cream truck, I'd feel like I missed something essential from growing up in the 50s.
That seems decidedly odd. Those things don't need to be unhealthy at all. Actually I don't suppose any of the places you mention have to be unhealthy. Like everything else, just a matter of making good choices.
ETA: We keep Marie Callender's (?sp) chicken pot pies in the freezer for those nights when neither of us want to cook or go out. They're really tasty.