IIRC there's an upper limit of about 20,000 miles per year for the motability scheme. That was a bit of a downer for my stepson, who covered about 30,000 miles per year in his wheelchair carrier.
We used to replace his car with an ex-motability adapted car every couple of years or so. It was rare to see more than about 25,000 miles on a 3-year old car, and even rarer to find anything of a service history.
Maybe the scheme operators, in line with some other large fleet operators, can tolerate an occasional catastrophic failure as a cheaper alternative (for them) than adhering to the manufacturer's recommended service intervals.