“What I question is the physical disturbance that can occur when surface of a car with film on it is rubbed with an applicator….”
This “disturbance” is necessary to exploit or break bond between dirt and vehicle surfaces (paint, rubber, metal, glass).
Start with dirty car.
“….friction world of car washing….we always…..flushed with water and detergent to keep it clean……water and detergent cushion….between the car and the wash media.”
That’s because conveyor is a continuous process where the equipment is arranged according to the steps necessary to clean, shine and protect vehicle surfaces.
Detergent and water applied first (reactivity) followed by friction to break physical bond and remove dirt.
Here, friction can include wash “material” or high-pressure water which is also a form of friction.
Brush detergent imparts lubricity to maximize material penetration and minimize possibility of wash material getting caught in cracks and crevices and it usually contains agents to help prevent dirt from re-depositing back on surface.
“If hand washing, we talk about the proper two-bucket method with only one wipe per panel before the mitt is rinsed clean.”
This is outmoded and inefficient as traditional full-service.
Conveyor hand carwashes operate similar to friction or hybrid conveyor except people are used to mitt cars instead of an automated multiple brush wash module.
Soapy cars are cleaned with soapy mitts top down, front to back as vehicles move by one by one. There is no time to wipe and rinse panels.
Professional hand washers (free-standing and mobile) usually begin by cleaning car with high-pressure water (with or without pre-soak injected) using self-serve spray wand.
Similarly, detailers do this to clean out wheel wells,
door and trunk jams, moldings, mirror cavities, engine compartment.
“Damage not that different from incorrectly hand washing an automobile.”
Waterless can cause damage (paint marring) if car is too dirty. Waterless OEM’s agree on this and recommend rinsing car first is so dirty.
Marring is microscopic marks imparted on surface that cause paint to have lots of little swirls or lines in it and over time makes paint look dull.
If car has good coat of wax on it (mil), marring from improper wash can be avoided to some extent. Most marring is easily removed with cleaner wax or orbital buffer.
A car without a coat of wax is actually more susceptible to damage from intrusive chemicals than from improper friction washing.
So, after prepping for a conveyor wash or a detail job or completion of touch-less in-bay automatic wash a thin layer of film will remain on most surfaces.
Evidence is eyebrow on windshield.
Lifting or removing this film from paint can be accomplished several ways as discussed without marring the surface.
Consequently, my opinion for express wax method when wash process is touch-less.