While I agree with you wholeheartedly MJR, I think you're missing the point.
It's a question of human nature and expectation, not of statistics and physics.
From the moment a child learns to speak it will bleat the words, "its not fair."
And they're right, it isn't fair.
However, the fact that there may a very good physical, statistical or legal reasons why it isn't fair cuts no ice with the baying masses of middle England, the very baying masses who's votes politicians crave so obsessively.
But my point was: it is fair. The speed limits reduce the numbers the heavy motorists kill and demolish, while not distracting the police unecessarily with much lighter vehicles going slightly faster that will very rarely harm anyone or anything else, until such point that the lightweights are behaving obviously recklessly or carelessly (which are offences even below speed limits, not that you'd know it from the way some police forces act).
For me, it's not a double standard, but a simple, fair standard: set the speed limits for each vehicle class based on the kinetic energy of its typical vehicle, so that it reduces death and destruction. This would be much fairer than the current Victorian-with-tweak-after-tweak system of speed limits which were originally introduced to protect road surfaces, not people!
All the baying masses see is cyclists behaving like loons, even if that isn't really the case at all, and the danger is someone somewhere will think there's a vote or two in it if they push for legislation to put a stop to it.
It's wrong, for all the reasons you cite, but that's the reality we may end up facing if we continue to take the piss, even if we know full well we're doing nothing of the sort.
But we won't ever stop all cyclists doing it. Heck, not even the threat of prison and fines has stopped motorists speeding left right and centre, so a bit of online scowling ain't gonna stop cyclists doing it in the few places they can. What can we do? Explain why any baying mass calling for same rules and penalties is being irrational, and hope that takes root somewhere useful.
Three fine young members of the baying mass stuck in a white van in traffic today offered to punch my glasses into my face (a crime) for daring to cross the road other than at a signalised crossing (not a crime in England) even though it didn't affect them in the slightest. How about we have some effective laws and policing against that instead? Maybe if the police weren't faffing about pulling over cyclists and mobility scooter riders for non-crimes, they might have more time to address real crimes on the roads.
