The unintentional consequences of speed bumps

Following on from my above post on OH&S gone a bit over board, I question the benefit of speed bumps with a 20 kilometre warning sign in so many streets where the posted speed limit is 50 or 60 kilometres per hour.
Add to these the proliferation of small traffic islands, chicanes, and roundabouts, I question the extra wear and tear it is on cars, damaged tyres on cars with low profiles but worse still what does it do to a fully laden fire truck on the way to fight a fire. Similarly it must slow the trip to hospital for an ambulance rushing to save a patient’s life. The same issue would no doubt face police vehicles. I could go on about delivery trucks with fragile loads and much more that it appears that road engineers are overlooking due to the irresponsible actions of a few.
Going back to the speed bumps in many places they are quite wide and I have witnessed pedestrians mistake them for pedestrian crossings and step out in front of the moving traffic when there are no signs either to the pedestrian or more importantly to the road users indicating that the speed bump is in fact a crossing point.
With the height and steepness of some of the speed bumps, it would be impossible to drive over them in a low rise sports car without causing damage to the vehicle’s skirts. While my car does not fall within this category I have witnessed the damage done to other motorists.
Again, I appreciate that reducing the speed of the traffic does reduce the road toll and is a good thing but I feel that it would be better for all of us if we stopped wasting all the money to put in these barriers and simply put in a speed camera.
The benefits would be the cost of the infrastructure would be lower, the government would make much needed more money from those that break the posted speed limit, emergency services would not be impeded in doing their much appreciated work, those that obey the speed limit would once again enjoy the pleasure of driving, while the incidence of damage to tyres etc. would be reduced.