You're right - the reality of the world today is that open-sourced code is slurped up by AI companies, all questions of legality/ethics aside. But this was not the reality of the world that existed when the code was licensed and released. That is why it is easy to empathize with code authors who did not expect their code to be used in this manner.

By far the most popular strings involve restricting restricting access. That is, viral licenses which require derived works to also be open source.