Eh, that level of rich doesn't care about a service contract. If their hyper-fancy, whatever gadget filled dishwasher/oven dies randomly because it's made like cheap shit and all the features are just checking boxes, they don't care, they can have it replaced within an hour, so the cook will just have to deal with only a single oven until then.

Which is why the rich are terribly undiscerning purchasers: the downside for them is some wasted pocket change. The time it took to consider the purchase already earned them more money than they will spend.

The appliances themselves however absolutely are built and designed to be serviced regularly to meet their expected lifespans.