What's up with that?
They're not you VC, SASS, zero marginal cost software first company. They're hardware manufacturers with physical product margins. The embedded project I work on only ships on a few thousand units/year, and it's only a small component of the overall system.
I think within that group of companies, the comp for embedded vs "software" isn't significantly different. "Software" just has FANG/VC backed salary inflation making the averages look crazy.
I work on Yocto-based products and am responsible for the platform, but working on recipes and kernel mods is only 10% of my work, and by the end you're not touching it at all. If you're making kernel and rootfs changes in validation you have a serious problem.
I'm not sure what projects need someone that is hacking recipes 40 hours a week.
The work is challenging and rewarding, but also grueling and frustrating like little else. Embedded wages are miserable. Almost any Yocto developer could immediately improve their quality of life by picking up a Ruby on Rails book and then nearly doubling their salary in a month or two.
That's essentially what I did and I've never looked back.
As long as that holds true, hiring good folks will be challenging.