Not sure when SAAMI or C.I.P. picked "Luger" and it became the standard. In the late 70's/early 80's, my circle referred to it as it 9mm Luger or sometimes 9mm Para(bellum) if we needed to differentiate between Makarov and Kurz/Corto/Browning/Short (had an acquaintance that refused to use .380 ACP and used the others randomly). Since then, seems like "Luger" has fallen out of favor colloquially in a lot of circles.
I agree with you. We used to use "pistol" and "handgun" interchangeably. Now that's a huge faux pas.
ETA: Since I'm corona-bored, I started searching for the history of the name and when SAAMI/C.I.P. standardized on "Luger". Nothing definite yet, but this doc with a history of headstamps and pics of old ammo boxes was interesting.