Apple doesn't prevent you working on side projects, open source etc. It's just that you are working so many hours under tight deadlines that you want to spend time with friends/family during a spare time.
And Apple absolutely allows challenging management and product vision. In fact I was involved far more in product design that I expected to be. Every team is different but it is a relatively flat structure.
Just a correction, Apple does indeed forbid employees from working on side projects, including selling software on the AppStore and most contributions to open source projects. This is made very clear during the employee's initial (and yearly) Business Conduct training. To me it's one of the major drawbacks of an otherwise great place to work.