[fiiv]

I am a freelance web developer working mostly as a frontender and in Node.js. I very often sell my clients on the idea that something I develop for them is better as an open source module. I then charge them for that time as if I built it just for them.

I do not consider this unethical as I always tell them up-front that I am doing this, and they are still getting this functionality. Several times I release the module under their name after as well (on Github and/or NPM), depending on their wishes.

As for the big players like Oracle, I am personally not a fan of the organisation but in their defence, they release plenty of open-source projects (Graal comes to mind: https://github.com/oracle/graal). And you know Facebook has a whole ecosystem they maintain in PHP, React, machine learning, etc. Their developers are paid to work on these projects. Google is the same way as far as I know.

So "maintaining for free" might not be completely free.

[smel]

Exactly no problem if paid by someone but should not be unpaid job.

When companies open source stuff are not for the greater good they do it because of economics. Just like in a bar when you get free salty nuts that help you drink more :D