There are also all of the electrical connections. Yes, it's all plugs, and shouldn't present a problem. But what if something isn't connected correctly, or else comes loose? Is the vehicle going to start throwing codes or warning lights? Or what if an airbag doesn't deploy?
I realize there is no other way to properly clean a vehicle interior that is allowed to get that filthy. But new cars are all but a nightmare of wires, harnesses, and connections. And a lot of these cars now have heated seats, which is even more wiring.
The connection is one harness, it doesn’t matter if the seat has an airbag, heated seat, or power seats, it’s still one harness. And if you leave it unplugged, yes it will immediately set an airbag light.