I can't see the liability issue, they are not that concerned when it comes to the few 100 people that die every year while using their phone in the car.
BTW, you can get i.e. uTorrent from the official Play Store. Actually the only time I did use was on holiday when I d/l an episode from a TV series - totally legal! Otherwise I don't watch movies on my phone.
But I give you another issue that sux about the Apple system: The country restrictions for apps. And I give an example:
A while ago I was in Germany, and Germany has a great cheap supermarket - ALDI. They have an app, but I can't get it because I had no access to the German iTunes. It's a free app too.