Who really cares what names the glasses in bars have? Canada, Australia and New Zealand all use the metric system, and all sell pints of beer in their pubs. Australia and Canada also sell schooners of beer, which come in 425ml and 946ml sizes respectively (where a schooner is 103ml in the UK).
No matter what system a country uses, there’s nothing stopping a bar from selling 568ml portions of beer, and giving you one of those when you order a pint.
> there’s nothing stopping a bar from selling 568ml portions of beer
The law (via regulations) stipulates what sizes can be sold. As an example, this[1] from 2011:
> The centuries-old cry of "fancy a pint?" may soon become "fancy a schooner?" under plans to relax the strict rules dictating drink sizes.
> Current regulations mean draught beer must be sold in pints (equivalent to 568ml), halves (284ml) or the little-known "thirds", and wine in measures of 250ml, 175ml or 125ml
Whatever the regulations about portion sizes are, they’re independent from the measurement units used. The government is allowed to regulate portion sizes of 568ml, 284ml and 189ml.
Also, is it really illegal to serve a 150ml glass of wine in the UK? That’s insane… A 750ml bottle of wine is supposed to have 5 glasses in it, not 4.28
No matter what system a country uses, there’s nothing stopping a bar from selling 568ml portions of beer, and giving you one of those when you order a pint.