This may seem like a minor nit, but I think there is a problem with using the term "unreliable" to describe UDP. The more commonly used term, and IMHO better term, is "best-effort" [1]. UDP makes its best effort to deliver the datagrams, but the datagrams may be dropped anyway. But it does not make UDP inherently unreliable.
[1] https://en.wikipedia.org/wiki/Best-effort_delivery