It would certainly depend on location, but BLS average salary data seems to point otherwise:
Plumbers $49K: http://www.bls.gov/ooh/construction-and-extraction/plumbers-...
Electricians $49K: http://www.bls.gov/ooh/construction-and-extraction/electrici...
Mechanics $36K: http://www.bls.gov/ooh/installation-maintenance-and-repair/a...
Welders $36K: http://www.bls.gov/ooh/production/welders-cutters-solderers-...
-VS-
Software Developer $93K: http://www.bls.gov/ooh/computer-and-information-technology/s...
Computer Programer $74K: http://www.bls.gov/ooh/computer-and-information-technology/c...