Software quality is a thorny issue. Many people are used to ad-hoc development, especially when working with simple applications on small microcontrollers. In reality, software quality is not art, it is methodical and tedious work. Experience helps, but there is no guarantee that any one person or team has enough experience to produce truly reliable software using ad-hoc methods.

There is a lot of bad software out there because nobody likes tedious work, and in many cases people don't understand the processes needed to produce reliable software. As a result, people have come to expect bugs in all types of software. For many applications this may be okay, but it is not okay when safety or your company bottom line is at stake.

For an indication of the processes involved in producing reliable software, take a look at:

http://www.ivv.nasa.gov/SWG/resources/index.html