The problem is that Police helicopters and Air Ambulances were brought in as a cost saving measure to reduce travel time to far flung incidents and rescue persons who were not conveniently near a road. Ground crews were cut back because they were no longer needed to provide an emergency response in remote areas.
Unfortunately, the cost savings that might have accrued were eaten up by increased costs of aviation. You can't cut back on servicing there, or ride roughshod over the rules governing duty times, unlike police drivers who frequently drove emergency response vehicles for more than eighteen hours in twenty four. Been there, done that. Chasing some scroat at 110 mph down a suburban high street after eighteen hours behind the wheel (including travel to and from home and five hours sleep) is not undertaken lightly. Neither is it particularly safe. Tiredness is probably worse than alcohol in its potential to lead to an accident. Many police officers have been killed in traffic accidents on the way home from work, with no other vehicle involved.
Times have changed and the rules have changed, hopefully for the better, but if you are going to have police helicopters, it has to be run and financed independently and not at the expense of cutting back on ground based staff and vehicles.
We have arrived at the point where police helicopters are necessary to cover the shortfall in investment in ground based resources. Same for air ambulances. If you do away with these services now, all the old remote bases will need to be set up again and a lot more money spent than wil be saved by doing away with helicopters.