The refurbished probably shouldn’t purchase those machines then if it’s a known issue. There’s a tradeoff here, and needing the owner to run a command to reset the machine seems preferable to having them be valuable if stolen

As you said, the problem is with the sellee. Apple is not the problem here.

Guess this is a good reason for repairers/resellers or buyers to ensure activation status on any Apple device they get their hands on. Easy for repairers/resellers to ensure since they tend to be directly in contact with the company and make it policy. For general buyers, they have to be proactive before making any purchases over an Apple device. As it's easier to contact the seller in question while they are actively selling vs hoping they'll respond post-sale.

Recycler should make it worth doing for them.

Getting paid sounds like pretty good incentive.

There's the incentive of "I'm confident that all my private data isn't on this machine any more", which I think matters.