Open source in practice, however, means 99% of users never contribute back anything. These developers just end up being exploited (particularly by well funded companies) by working for free, building something valuable, fixing people's bugs, but not being paid for their time.
That's what I want to change with Supported Source, an alternative model to open source. Open source developers: don't give your code away for free any longer! If companies are willing to use your code, they should pay you (it can still be given for free to small companies or individuals) Check it out at https://supportedsource.org/
For example, usually with the professional version of compilers the source code was also there, just not on the student/hobby versions.
Just recently I got hold of an old Turbo Pascal 5.5. brochure where Borland explicitly referred the availability of the source code on it.