"asking for a hardware shopping recommendation" should be included. Don't know why it is not explicitly mentioned when it's a valid off-topic close option.
"asking for a product, service or learning material recommendation" - Can we edit that to read "product (software)" instead? I've had an experienced and relatively high rep user argue with me that FOSS does not fall under any of the three categories and so asking for it is allowed.
It comes under product recommendation. It's actually been disallowed longer than software recommendations.
A software recommendation is a software recommendation, free, paid, or if you get paid to use it. The correct way to ask for software is to ask about a problem, and the software should be part of the solution, not the solution. The user in question is wrong.
That said, yeah, there's probably ambiguity, but partially in the sense that people are reading what they want to read, or not at all.