The point is some people don't want to drive or can't - many from overseas don't want the stress of driving on the other side of the road, different traffic laws etc., plus anyone under 25 can't easily rent a car without taking out a mortgage, so there are plenty of reasons to not drive in Orlando.
But with a combination of reasonably priced cabs, Lynx buses, hotel shuttles and Disney buses, it's very easy for a non-driver staying off-property to get around almost as quickly as anyone staying on property and using the Disney buses exclusively, for far less cost.