As a resident of Montgomery County, MD, each of my bikes is required to be registered with the county, and each of them receives a license and a number plate which must be attached to the bike frame. This process costs me nothing and is paid for by county taxes. If that's what people want to spend their tax money on, I'm fine with that. I think it's stupid, because motorists are essentially paying the vast majority of the bill for my license, but hey, that's apparently what they voted for, so whenever I get a new bike, I happily license it.
By the way, the whole thing is a joke. The police don't ticket folks who don't license their bikes, the license plates are tiny (they can't be read unless you're closer than 5ft away) and can be fixed anywhere on the frame, and the numbers are not used in any way to promote road safety or to prevent crime. It's just a stupid boondoggle.