You're using data from 1944, based on fixed-pay government jobs, to support a claim that private sector software engineering is well-paid, in 2024, due to "IQ gating." The irony is hard to miss.
2. a job doesn’t necessarily pay well just because it does require a high IQ. Scientists in a research lab, professorships, academic research all likely have more intelligent people on average yet don’t pay as well as software engineering.
3. The study still shows a routine and reliable difference in average IQ between those who work in manual jobs/trades and those who work in science/engineering
Software engineering in the US is well paid, yes, partially due to economic effects and impact of software in and of itself, but it is, especially in FAANG, a profession with a very high concentration of people near the higher end of normal and above in the IQ spectrum, which leads to implicit selection criteria regarding intellectual capacities in employment.
In any event there is more recent data (1992-4) that confirms that the differential is still present. This is maybe unpleasant to confront because it's self-congratulatory and has obvious class implications, but it's also pretty obviously true.
See page 89 / figure 12:
https://users.ssc.wisc.edu/~hauser/merit_01_081502_complete....