"That's the way we've always done it!"
Using a pressure washer on the interior was a common practice for used cars in the 40' and 50's. in those days most cars had rubber mats, not carpet and plastic seats.
There were not electronics so no problems.
However when carpets were added, fancy cloth interiors, and electronics you have a problem.
But because far too many Detailers operate on the philosophy of, "that's the way we've always done it," they keep doing the same thing.
To show you how crazy this is in the Middle East they remove the seats and carpet shells and the seats. Pressure wash the interior then pressure wash the carpet shell, the seats and let them dry in the desert sun.
When I asked why they detailed like this I got a "that's the way we were taught and that's the way we've always done it."
When I asked about the electronics on the interior & on the seats I got a blank stare. These fellows were imported labor and were taught by those before them. The blame rests with management who pays no attention to what is done and how it is done, and probably don't know either.
That is typical in USA dealerships and carwashes with detail operations. No
training, no supervision.
But Detailersare not free from sin either. Far too many Detailers refuse to embrace new technology. I recall back in the early 80's most refused to embrace the velcro backer plates and pads preferring to keep using the bolt on pads. Then came the foam pads and detailers again saying they have always used wool pads.
Ask a Detailer who does not have an extractor why they don't have one and they say, "don't need it." And they launch into a long dissertation why they aren't needed.
It is comfortable for all of us to keep doing what we have always done, but to grow we have to embrace change and new technology even if we can't afford it.