First, a business does not get to charge customers for evey working hour of the people providing the service.
There are idle times, lunch breaks, training sessions, jobs that need to be done again (through no fault of anyone), annual leave, and the list is long.
Second, a business does not get to charge customers for all of its staff.
On top of the mechanic working on the car, there will be service managers, directors, service advisors, receptionists, apprentices, a cleaner, and even the guy that washes the cars following service (two guys probably, as the cars need to get washed also when the guy is on holiday or sick leave etc).
The hourly rate that they charge the customer has to pay for the hourly rate of all those people, not just for the one mechanic.
And the above only relates to staff salaries. It does not even touch on the costs of premises, insurance, garage equipment, and so on.
I am not suggesting a collection for MB dealers... all I am saying is that the wages that they pay the mechanic who works on a customer's car is an almost irrelevant figure in the big scheme of things. There is little that can be inferred from this regarding the business' overall profitability.