Funny - despite having a license for decades I had to rewrite all driving exams to get my motorcycle license.
I don't recall a single question about sharing the road with cyclist. There was about 4 questions about drinking and driving while on probation...
The problem with government regulation is that the point of the regulation is quickly lost and the raison d'ete for the program becomes simply tax revenue and job protection for those hired to administer the program. Then the insurance company will force their way into your pockets. Then it never ends.
There is no reason to separately license bicycles. I do think that existing licensing exams should have much more cycling related content to ensure drivers are aware of the rights and obligations of cyclists and motorists on the road.