I think it's more because there's a lot of software that's too cheap to charge for, but has too many edge cases for the average programmer to get right.

Logging is a perfect example, server-side logs are all handled by free frameworks (too cheap to charge for, but everyone needs it), but client-side is often handled by companies (just complex enough to make money on).

The former is often handled by LBIPs like Eric, where-as the latter is either written in house (usually badly) or you get something like Sentry.

If the useful open source software development work was not scarce these maintainers would certainly not be under immense pressure.

To boot, the entire idea of post scarcity is preposterous. Until the theorized heat death of the universe, there will always be uneven distribution of resources and some things that are better than others.