If something looks like a duck, walks like a duck, and quacks like a duck, what is it?
The answer, of course, depends on whether or not the name `duck' is a trademark! If it is, then the closest that something can get, without permission of the owner of the trademark, is `duck-like.'
`UNIX' is a trademark of The Open Group, and NetBSD has not been branded with that trademark. Therefore, NetBSD is not UNIX. We refer to it as `UNIX-like' or `UN*X-like.'