There are many closed source applications that have been removed from the Google Play catalog for various reasons.
Often this reason is the cessation of further development and maintenance of the application.
Why don’t these people make the code open to everyone if they don’t need it anymore?
This could bring great benefits to all people, but everything that was once created simply disappears.
Why do people not give away that neglected guitar/motorcycle/boat that’s been sitting unused for free?
Because one day they’ll get to fixing it up surely, and besides they’ve sunk so much time and money into it that it must still be worth a lot.
I understand your point XD but want to emphasize, software is NOT like tangible items, and any analogy to them will fall flat.
Giving out the source code to an abandoned application does not mean the original owner doesn’t still have their copy.
By just dumping the code online, the software has the potential to be worked on by other people. This can benefit everyone, including the original developer.
Even so, there’s plenty of valid reasons to not do it. Licensing issues (did anyone else work on any part of the project using a different license?), pride (no longer being the “owner”), getting it online (choosing a license, getting it online, it all takes at least some time and effort), or just plain “I don’t want to” are all valid reasons.
I have projects. Games that were in the google play store. One had hundreds of thousands of downloads. Then Google pulled it as I didn’t maintain it. But, I have to pull artwork out, sound effects, etc that can not be included. And that’s just time. I don’t have much of that, that’s due sure.
Because their code is a mess, ugly and full of bugs, that is better burn to the roots that trying to fix it.
In addition to other reasons already given, commercial software may contain licensed code, libraries, assets, trademarks, and other IP that cannot legally be given away for free, or under an open source licence.
Sure, it may be possible to strip those things out, but that may leave the software broken or fundamentally changed, and it may be a significant amount of work to do, which am author or publisher is not likely to spend on abandoned software, especially if their free release would compete with any current products.
It’s probably unmaintained because they don’t care any more, or don’t have the time. If they don’t care or have time, they are not going to spend the effort and time required to open source it and publicise that fact