There are quite a large segment of engineers later in their careers who would be interested in this kind of arrangement, especially some engineers who are paren

There are quite a large segment of engineers later in their careers who would be interested in this kind of arrangement, especially some engineers who are parents of young children. I suspect the demand for these kind of part-time working conditions outstrips the supply. My experience is from the labour market in Australia, the situation here is a bit different than the US as our healthcare & health insurance is decoupled from employment. There are some very sharp and experienced engineers out there who are not willing to work full time roles any more, and this eliminates them from the running of the vast majority of advertised roles at companies that will only consider people available full time. It's not uncommon to see senior engineers negotiate part-time arrangements after being at a company for a few years.