this is the order of importance that should guide urban road facilities:
1. Safety of vulnerable road users, (pedestrians and cyclists)
2. Safety of motor vehicle drivers,
3. Convenience of vulnerable road users,
4. Convenience of motor vehicle drivers.
If a facility puts, say, the convenience of motorists ahead of the safety of vulnerable road users, it is reasonable to disregard it.
Velorution has an interesiting post commenting upon David Cameron's cycling misdemeanours: Velorution: Safe Cameron.
