Yeah, if cleaning up were as simple as that, you wouldn't even need OS support, the drive could just trim itself as it went. But it's been 20 years since anybody designed disk geometry into a filesystem, and while TRIM may not be as complicated as all that, it still requires more bookkeeping than the OS usually does.

Optimally using TRIM, such that the OS will defragment the 512K blocks online instead of reusing them, is even more work, and I'm not sure that's what Windows is doing. They're just issuing TRIM opportunistically, AFAIK.