My car rego is around $900pa. So what would bike rego be? $50? $100? - Couldn't be less, or it would cost more to administer that it brings in. An adult who uses a bike as transport, or serious fitness would undoubtedly pay that.
But what about kids and adults who use a bike for recreation? So will a family of four pay $200-400 pa to register their bikes for occasional use?
Bike riders have virtually the same rights and responsibilities as other road users currently (increasing fines for bikes to be commensurate with motor vehicles will correct an anomaly).
Enforcement of the rules? Bikes are highly unlikely to be caught by automatic detection systems. They're highly unlikely to pass through a speed camera at enough speed and get fined and just as unlikely to be detected by a red light camera. So registering them would make no difference. Registering them would also make no difference for police to manually enforce regulations.
So IMO it comes down to "why should bikes get free road access"?
A small motorcycle is about $130pa, so if cyclists paid $100pa it shouldn't be an issue.
Enforcement of rules?? Just because it's harder it doesn't mean they should not pay any rego. First and foremost rego is a personal injury insurance.
Cyclist do cause accidents too, so why should they be exempt?
My cousins daughter who lives in Perth (at one stage a high ranking tennis player) was run over by an adult cyclist who mounted a footpath, and ended up fracturing her 'playing' shoulder.
There was no insurance for her like there would have been had she been in a car that smashed into her.