And proficiency tests for riders? Mandatory third party insurance?
I'll ask this in all seriousness. Why not?
Would either of the above, some type of registration document or paying a road tax be beneficial to us cyclists?
Before any knee jerk responses, prepare a list of Pros and Cons. Study it carefully. What did you manage to find that could be put under the heading Cons?
Rider training may go some way to reducing accidents. At the risk of courting vitriol, would anyone undertake if they'd been educated on the risks.
Since we're on public roads/tracks and often on private property, the 3rd party (I'd go further and opt for fully comprehensive) cover would be a good idea.
Registration documents would undoubtedly reduce theft.
Number plates (which are compulsory in some countries already) would allow for easy identification.
Paying 'road tax' would completely remove that hoary old chestnut.