Maybe it's a colloquialism, but where I come from in Canada, it's not uncommon to ask for two beer, please. Much the same as "I saw two deer or two moose." Oftentimes, in a restaurant, a server will ask, "What'll you have to drink?" The response, if there are a couple of people at the table, may be, "Two beer, please." whereupon the server will ask, "What kind?"
In Dutch is even more complicated. You never ask twee (two) bieren (beers) but always "twee bier" pronounced like (t way beer) But if you want small ones you'd ask "twee biertjes" pronounced like (t way beertjuhs) plural and never "twee biertje" singular. Anyway you all know the most important first lesson Dutch now.
Consensus seems to be against us, but I am with you MichaelJay122020. The only way I would say I wanted "two beers" would be followed by "one Presidente and one Presidente Black" (insert other appropriate beer to taste). This does seem like a Canadianism and by worldly standards that I can find, AKA the internet, beer as a unit of drink is counted and pluralized as "one beer, two beers, three bears, for beeers, etccct". But we drink more beer than most, so maybe that explains something, like trying to hide how much we drink by making it sound like less.
I'm from Canada and would probably use the singular, but I've heard it said both ways lots of times. And if you want to see how contested a subject this is, check out this discussion at a site for English teachers, who do not agree on this issue: https://crofsblogs.typepad.com/english/2005/06/beer_or_beers.html
They never say two beerS? Yes, everyone says two beers. Native speakers of English say two beers, three dogs, eighteen cars. We add -s to words to make them plural.
If beer had an irregular plural it would be listed in a dictionary.
Grammatically two beers is correct but in Eastern Canada, especially, two beer is more often than not what one hears when ordering. I do agree that using grammar correctly is very important in maintaining clear communication but changes in grammar often occur over time when a particular usage becomes very common.