DW and I have run into this exact thing repeatedly. We have been told by bartenders (and observed firsthand) it has to do with people not knowing what they are ordering. Someone orders a tom collins and (correctly) wants it made with gin, and the next person comes up and orders it because they saw it on TikTok, but assumes it has vodka in it because it was in a trendy video.
and what they are seeing is a vodka sour, not a tom collins.
I almost always have an issue when I request a dry gin martini, up with a twist. I always get asked if I want vodka or gin, and then I repeat myself. I dont blame them for going on autipilot, especially when you are serving a large population that *thinks* that knows what they are ordering, but in actuality is getting the drink order incorrect.
I have also witnessed someone trying to order a 'tequila sour', and confusing the bartender. They were next to me, so I went 'that's more commonly known as a margarita".