Kicked in during COVID, and is (like COVID) hanging around unpleasantly.

It’s a fairly good barometer of what kind of pub you’ve walked into. Pubs with a decent regular crowd will wait at the bar as in the beforetimes, with the bar staff working their way through the meta-queue - and the staff will encourage this behaviour. Pubs with a crowd of casuals or tourists seem to tend towards queueing which the barstaff do nothing to correct, and should generally be avoided for any serious drinking.