There's a lot more overlap than I'd have predicted 30 years ago.

There are very good open source databases, content management systems, web servers, full text corpus search systems, operating systems, and 100s of other "kind of boring" things that a 20 year old version of me would assume people would need to be paid to create. (Some of those are a crossover where a substantial portion of the development was originally paid, of course, but many others are not.)