Interesting one, this one.
There IS far too much "trivial" car use - i.e. journeys for the sake of it because you have a car, where you could make do without that journey or at least with a much shorter journey if you didn't have that car.
However, there are things for which cars are essential. We could not, for example, manage our woods without a motorised vehicle (and quite a heavy one at that). We have to lug equipment back and forth from the house to the woods e.g. generators, large brush-cutters plus the petrol for them, chainsaws and so on. We do leave some things e.g. the tractor, in the barn, but we can't leave very portable equipment there because of scrotes who try and break in and steal stuff. We cannot transport this equipment by bicycle, it is just too heavy, and it would not be possible to stack it safely.
I also could not do my personal training business or nordic walking classes without a car as I could not transport the equipment or poles by bicycle. It is possible to carry one set of poles by bicycle (I know, I've done it), but not enough for a whole class.
My mother who had MS and was in a wheelchair managed to remain independent for years using a Motability car. She had to have it converted to carry her wheelchair, although she transferred herself into the driver's seat to drive with hand controls. She didn't make unneccessary journeys, just to the nearest shops or supermarket, and to visit us.
Like people say, there are non-obvious disabilities which require Motability cars, such as lung disease - I know, I suffer from one (cystic fibrosis). Thus, although I can cycle solo without luggage, I could not possibly carry large shopping loads on a bicycle due to the lung damage I have. I am lucky in that most of my local shops could be reached by bus, but many folk living in the villages outside town have no bus service at all. In my situation, a car or taxi would be their only option to get out of the house.
I'm currently temporarily disabled by a broken knee. I am going stir crazy as I'm completely limited to my own house, or a few of my close neighbours. I simply can't get anywhere else on crutches. At present I'm extremely grateful to have a car (and a 4x4 at that) so I can not only get to our woods, but also be driven round it to enjoy the birds and flowers and trees. Without a car and somebody to drive me, I'd have been totally stuck in the house so can appreciate what this is like. I am lucky. I will get better and be able to cycle and walk again. But I can appreciate how people feel who are stuck and who would remain stuck without a car (or a probably unrealistic regular public transport service to all small villages in the country).
So, I'd prefer not to use the car, but sometimes have to. Where I don't have to, I don't. I do cycle or walk into town or to the woods where I can, but if I have to carry equipment, I can't. I do appreciate the value of cars to those with temporary or permanent disabilities.