I've never paid that little
for any service. I'd say you got off cheap! Even for an A service they have to check and test dozens and dozens of systems in your car. MB labor costs are higher than many others because their service technicians are required to have much more training and formal education than other's "mechanics."
Welcome to the board!
I've seen this from both ends. As a consumer, paying what I think is a huge rate for something I think is simple, and having taught mechanics in dealerships and independent shops and seeing their concerns.
While the dealer may charge by the hour, the tech gets paid piece rate or flat rate. On the one hand, they can come out ahead for some repairs, fixing them faster than the "book" allows, however, there are many times that they spend hours longer than what they get paid, because of problems that are easy to solve with a part on a bench, and not so easy under the car, with 6 pieces of equipment rusted on, that just happen to be in the way.
As far as the comment that the MB tech's are required to have much more training, that's not only not true, but the reverse is probably more likely.
The average independent, even if he specializes, works on several brands, with all models, produced and has to know the ins and outs of all of them to make any money.
Its the nonsense fees that add up to the big bill that are outrageous at your friendly MB dealer. Hmm... 30 bux to remove the tire, 60 bux to replace the tpms sensor, 40 bux to replace the tire, 30 bux to balance the wheel again. 60 bux to turn on the ignition... oops I mean activate the reset protocol. 60 bux to take the vehicle out for a test to make sure the tpms resets, and another 60 to make sure it works the second time you reset it..... ten percent for shop supplies, standard, even if there were none used ....think I'm kidding? Uh Uh.