At least in the UK it's a legal requirement to use marked glassware when serving beer, cider and wine. (Or to use a marked measuring cylinder and pour that into the drinkware, which is sometimes done for wine.)

It's also the law in at least some EU countries, although I haven't checked beyond Wikipedia: https://en.wikipedia.org/wiki/Fill_line

In true British fashion the requirements for draught beer and cider are in pints, while wine is sold in millilitres.