This is what the car wash owner said in his letter to me:

"We are a member of the International Car Wash association that has a
liaison committee with the various auto manufacturers. The car wash
industry has discussed this problem with Volkswagen with no immediate
resolution. The issue is that the retainers can come loose, sometimes
the result of maintenance, sometimes that of simple road hazard issues.
In the cases I have dealt with the customer is unaware of this condition
that makes the guard hang lower than designed causing it to catch on the
conveyor that pulls your vehicle through the wash. The conveyors are
built to accommodate all types of vehicles including Beetles."

Has anyone ever heard of this "issue" with Beetles and conveyor car
washes? Does VW have any disclaimers concerning Beetles and car washes?