But aren't their also mid-end appliance manufacturers that make very reliable appliances?

Who are the high-end ones that are really that much more reliable??

There is a curve. High end appliances don't have enough volume to shake out all the problems and fix them in the next design. Mid range does.

Possibly we're thinking of different degrees of high-end. I'm thinking Miele and similar; definitely very expensive, but relatively high volume. There's certainly a tier above who make stoves that cost more than a car, and your concern would certainly apply there.