I used disabled toilets often. With 2 young kids and a huge pram it's much easier to use disabled toilets than normal toilets. I will use parents room if there is one though. I rarely see anyone in a wheelchair when out shopping so figure the chances of someone who needs such a large toilet area rocking along when I am in there is very low. Yes I know there are others besides people in wheelchairs who may need a disabled toilet. Worst case scenario someone can knock and wait a few minutes or use the single toilets as a one off.
In my defence most of the disabled toilets also have baby change tables in them so someone somewhere higher up has also come to the same conclusion as myself about cost/benefit/risk of sharing.