If we are talking about washing a car with a pressure washer and the paint is coming off, it means you are doing it wrong. Too much pressure, wrong nozzle, wrong angle, too close to the finish, or hitting edges of chipped or damaged paint.
My point is, you CAN power wash vehicles, even if they have decals or striping on them, WITHOUT damaging the decal or stripe IF you do it right, even though it is possible to remove the decal or striping with a power washer.
The orange lift you showed with damaged paint had chalked, old paint on it. And if you have a business repainting equipment, you were probably purposely trying to take the paint off it.
I've had plenty of dumptruck beds, implement trailers, asphalt tanks, and so on that even using Windex on them caused the paper towel to have paint color on it. So I don't think everyone uses Imron on them (which, by the way, can be removed with a power washer if you hit it at the wrong angle and too close. Plenty of Formula Boat owners have discovered that over the years.)
Back to the OP, if it were my customer, I'd ask which car wash he uses and take the vehicle there for the operator to see what they claim the carwash did. Unless it's a self wash place. You can do that with a self wash spray wand if you try to.