There AREN'T that many things to go wrong.
The reason it SEEMS that way is that people who frequent this site here about problems and how to correct them. That's why we post here. So, this makes it seem as if every MB that's ever been on the road has a rash of problems.
As an example, a problem that is considered common, such as the infamous a/c evaporator on the 124 cars only occurs on about 15 to 20 percent of the cars. It is considered to be common here, but you have a four in five chance that it will not give trouble on YOUR car.
If you were a veterinarian and saw dogs come into your clinic several times a day that are sick, it could start to appear that ALL DOGS ARE SICK. But, that's just not true, it's just that the veterinarian only sees the dogs that are sick. There are zillions of them that are at home, healthy, chasing sticks for their master. The veterinarian isn't seeing those dogs.
Enjoy your new (to you) car,