Translation into executable format is almost always done fully automatically by machine. For many languages, this translation is simple and requires little sophistication in compilers. Once someone writes the build system, it can be made easy for untrained people to use. There is no intervention required by the programers after the code and build system is complete. There's no human element.
Different programmers implement a formal specification of an algorithm in different ways.
The FIPS on the Rijndael cipher. I'm assuming that porting and coding software is something done by trained people. But, once that is done, many times compiling or installing is potentially as easy as pushing a tape into the tape deck. One of the responses to an earlier version of this email thought that there was much more of a human element in building. Edit and correct away.