Using those examples when comparing software and hardware engineering _in general_ gives a skewed perception of things. Three of those companies are only interested in hardware as a way to optimize their (incredibly profitable) software business, and Apple/NVIDIA are two of the three largest companies on earth. That's a teeny tiny slice of the job market.

I'd bet that if you averaged out compensation from the top 100 paying companies for both hardware and software engineering rather than the top 5, the software number would be nearly double the hardware number. Once you start look at "normal" companies, the difference in margins between software and hardware and its effect on pay becomes very clear.

Check out the stats on apples margins on hardware vs their services and software ;)

And arguably most of these companies (minus Apple and nvidia) have software and services as their bread and butter, not hardware.