As far as licensing.
License riders?
License bikes?
Two different issues.
Are you going to license 3 yr olds? Make sure they know the rules of the road before taking their push bikes out on the street? Or is it the push bike that needs to be registered?
Maybe have a rider safety class and registration for 14 yr olds (pre driver's license)? Actually, that would be a good thing to do as a mandatory class in school. Also bike maintenance.
Does one differentiate between the riders that ride < 100 miles a year, vs those that ride > 5000 miles a year?
My old bike was stickered twice.
The local PD sticker was voluntary. They registered the serial number (actually, we stamped a number onto the frame since it had none).
I believe the college campus also required registration. I apparently didn't register it when I was in private on-campus housing, but it appears as if I registered it when I shifted to off-campus housing. I hope they've kept the records, otherwise that registration is useless. 30 years for the college campus, and probably 35 years for the local PD.
I suppose doing a one-time minimal fee registration isn't bad when one has a single bike. But, it could be a bit of a pain for multiple bikes.
It might help a bit with bicycle theft tracking and recovery, but would need to be fairly widespread across the country to be effective. Getting bikes sold and not re-registered could be a pain problematic.
Ideally it would be a self-supporting program, with administration and fees being equal, but I could imagine high administration costs, and a slippery slope for increasing fees as governments look for more tax revenue.
As it is, I'd rather see the governments encouraging as many cyclists to get on the road as possible, which means making it as easy to get on the bikes as possible. I.E. no added fees.