it's a lot cheaper (and better imo) to just build a bike trailer. You can take it back off when you are done, and it can go on multiple bikes. Not to mention it's not $3000.

Also, locking that thing would be a pain. You have nothing to lock the front wheel to..

I am not saying its perfect, however, it is a novel idea and I think is at least a step in the right directions of at least trying to remove some dependency on cars.