They just require a bit more attention.
For example, if you drive a Honda or Toyota you can skip out on transmission fluid changes, and nothing will really happen (my dad never changed his transmission fluid on his 1998 Toyota Camry that we sold last year with 195k miles on it and the transmission shifted fine). Skip out on things like this on a BMW, you'll be sorry.
Fluid changes are part of normal maintenance items that a lot of people tend to skip. But usually on Asian cars skipping transmission fluid service won't do much harm from what I've heard.
The issue that technicians have with BMW is their use of cheap plastic components within the engine bay. They're scared to death of breaking connectors or actual connections during the parts removal process and having to deal with the accompanying friction with the customer over who pays for their replacement. Take a valve cover gasket on a modern BMW I6. A $50 crankcase breather hose must be removed. It is connected to the VC via barbed fitting and snap connector at charge pipe on the other. By the time the VCG needs replacing the breather hose has become brittle. When it come to removal the hose can crack, the barbs can snap, and the connector at the charge pipe crack requiring a new section of charge pipe.Watch this video instead: