[janm]

Yes, this is true: A lot of embedded code is poorly tested. Even more is poorly designed and written by poor programmers (like most software.)

Some people have to deal with the machine, and C is a good model of the machine. Even reliable systems have some core in C (or an equivalent) that provides an abstraction where higher level abstractions can be expressed.

Testing isn't the ultimate solution; some people are just able to use the machine better and produce better code. Testing crappy code doesn't really help. A subset of developers produce tools where others can produce systems with less risk by providing appropriate abstractions.