1) Added cost gives no incentive to car drivers to start commuting by bike, which would have at least some effect on congestion, pollution and health. Maybe no

1) Added cost gives no incentive to car drivers to start commuting by bike, which would have at least some effect on congestion, pollution and health. Maybe not directly, but the funds generated from licensing and penalties could go towards education programs, tax rebates for those who start commuting by bike, improving safety for cyclists, etc. My guess is that there's a network effect to be had. Once you hit a certain density or,(ugh) critical mass of cyclists on the road you get a point where it is safe and socially-accepted enough that it will become commonplace, and everybody wins. 2) How do you enforce it? I don't know, I have no experience in the machinations of government. However, I'm confident that if you tell state and municipal governments that they could generate revenue off of it, they will find a way.