That's real world economics.
A lot of people bidding on those cars are buying the nostalgia /image. Kinda a like a new pair of shoes.
They are not the types that will build/work on a car. Like most people,they just want to own and drive the car.
The auction is easy access to that finished product they desire.
A few years ago one of the guys at work came down with a serious case of "muscle car disease" and wanted a Chevelle SS real bad.
All the turn key finished cars were 20 to 30K+ and some of those were restored originals.
He complained it was too much to pay for an old car . I told him he would sink that much or more into anything less even if he did a lot of the work himself and scrounged for parts.He convinced himself he could do it cheaper so he went ahead and bought a beater with a wore out 350 for $8,500 and then proceeded to dump money into it (paid for a lot of work he thought he could do himself) until he had a 72 454 SS clone. Car turned out nice but by the time he was done he had 25K+ into it not counting the
original purchase price.New engine,new trans,new interior,new suspension,wheels & tires,
body work & custom paint. He found out why the turn key cars cost what they cost.
But he is happy with it and drives it occasionally.
Some wise guy once said "if it has wheels or tits it's gonna cost ya"
Step Away From The KOOL AID !