I'm sure they could com up with removable upholstery (or upholstery covers) that they can clean separately and replace as often as needed. Its not a huge leap from floor mats and seat covers
I looked at a couple cars so don't remember exactly which. I think is was a Subaru Forester. I was sitting in the back seat checking things out and noticed a tiny line along the back of the driver seat. Turns out it was an internal zipper with the ends tucked near the bottom. It think if you pulled those up, the whole back flap of the seat cover opens up.
