The irony is that a lot / most / all? of these apps and services are built and run on open source software.
(is fully closed source software development even still a thing? is there any popular propriatary programming language / editor / runtime / ecosystem?)
Non-copyleft free software licenses such as the MIT license explicitly grant anyone the right to use the software for any purpose, including for things the original author doesn't approve of, and including building closed-sources apps and services. This is the point of open-source - the original author contributes their software to the open-source commons and then doesn't track who uses it for what. Recent attempts to create licenses that do impose restrictions on Software Freedom 0 are attempts to do ideological advocacy for various leftist causes by means of software licenses, and are not free.
Copyleft free software licenses such as the GPL explicitly grant anyone the right to use the software for any purpose, as long as they also extend this right to their own software. The intent of this license was to infect any novel software built upon GPL-licensed software, forcing it to become free as well; in practice any organization who wants to build a proprietary app or service simply avoids GPL dependencies (or blatantly violates the license terms). Empirically, software companies care more about avoiding being forced to release the source code of their own proprietary software more than they care about using the exclusively-GPL'd software commons as a dependency, and this isn't a problem the license itself can solve.
I'm talking about licenses like any of the ones listed at https://ethicalsource.dev/licenses/, which make the source code available but prevent people anf organizations from legally using it unless they act in accordance with various types of leftist political demands.
Funny how I've seen it twice now that when asked what license a published software would adhere to was GPL, but only for non commercial and "you should contact us for commercial use". So you have both he GPL poison pill and non conformity in one package!
I think that's a good option. You get all the benefits of open source as long as you pay it forward. And if you don't want to pay it forward to your users, then I'm not paying it forward to you. This is reciprocal altruism.
Imagine if I as a hobbyist take this project A and mix it up with gpl code from another project B. I release this mashup as project C. Now some company contacts me and wants to use C commercially. If I say yes, A will be upset. If I say no, B will be upset. A contradiction!
Conclusion is that gpl but only for non-commercial does not work. They need to use a different license to get something self-consistent.
There's a part in the GPL that says you're free to discard any terms other than the GPL and specific ones (like attribution). So if they really did apply the GPL, you can use it commercially, but only under GPL terms.
I don't think it's that bad. Most commercial enterprises don't want their commercial products to be under GPL terms, so they'll pay for the license regardless. You should really fix the SaaS loophole by using AGPL instead though.
