The appearance of being on the go is much more crucial than the reality. Partly it's a health thang. Nobody in their right mind wants to spend an extra second breathing what wouldn't pass for an atmosphere on a blatantly poisonous world like Venus or Jupiter. Partly it's a social thang. You're either isolated, doing your own thang by yourself, or you're part of a larger group, which is either on wheels, or packed in a set of chairs somewhere.
Facial contact is too important to trust to pediatrally-oriented groups.
And finally, you just get tired of carrying the stupid bolt cutters necessary to get through all the stupid chain link fences that are always in the way. All rights reserved.