Cars also have toe in and camber, and the amounts of each may be different front to back, so not rotating your tires can cause unusual wear patterns and lead to more problems than just going bald.

Bike wheels don't have toe in or camber (well I suppose the do while you are in a turn) so their wear will be much more uniform on the tire itself. Also the wear pattern will be very similar front to back except for how fast that wear occurs.