They can't forbid you from working in your off time but now you're their employee -- you work 8 hours straight during which you're not allowed to work for a competitor or you're fired. If you want to work for Lyft for another 8 hours after that, go ahead. But Lyft isn't going to let you work for 2 hours and pay you benefits.
That wasn’t the point. The point is you won’t be able to work for Lyft because they won’t take someone on to work 2 hours a day because it costs too much. So you will work for one or the other and you will have zero flexibility in the matter.