Why so many very low milage Audi, Mercedes for sale as CPO?

Only low miles cars qualify for CPO.

I can understand that, in the case of Audi, (very reliable) and maybe MB and BMW. However, I see the same for Acura MDX (for instance) which has had a declining reliability record, particularly since they went to the problematic 9-speed transmission. I see owner postings where transmission was replaced with LESS than 5,000 miles, causing owners to be upset and wanting to return/sell/trade the car. Acura used to be very reliable.