Perhaps I've been getting my editions mixed up but there's also the spell Protection from Evil and Good in 5e, which is somewhat similar to the older spells except that it offers protection "against certain types of creatures - Aberrations, Celestials, Elementals, Fey, Fiends, and Undead" instead of a blanket protection against any NPC or monster with the appropriate alignment.
That said, I'd still rather have alignment implemented than not.
Yes, Protection from Good/Evil/Chaos/Law only affects dyed-in-the-wool beasties of that alignment now, effectively assuming that the listed creature types are of that alignment without worrying about their actual stats. It is certainly no good against the more background alignment of most characters or monstrous humanoids.
The same goes for Detect.
