dunno; maybe because shoes are not vehicles? the day we all walk fast enough to require helmets and lights after dark, i could sort of see it.

in the meantime to the op: i wouldn't do it myself. partly because i'm not interested enough in drinking or proving anything about my abilities ui to care if a few beers means finding some other way of getting home. but mostly because i think it would make me feel like a hypocrite: like i want all the privileges and rights of being a vehicle when i'm on a bike, but i'm not prepared to ante up the responsibilities in return.