Eh, it's also much easier to slap a client-side detector on because you can use generic detection methods. When you're doing it server-side, you have to rely a lot on statistical analysis and it's all game specific.
In the end you can, of course, reduce it all to not shelling out money, but there is some nuance too.
But you couldn't release your own projects based on this under pure MIT or Apache-2.0. Presumably you'd need to include the same restriction about selling on Atlassian's marketplace.