I honestly think that it's negligent on the part of public health folks to continue the practice. Saying "Drinking more than 2 drinks in X time will cause you to be legally impaired" is actively encouraging people to unwittingly drive drunk in a culture when a typical ABV for beer is about twice what it was when those standard were originally calculated, and non-highball cocktails typically contain at least two shots of liquor.
"Unit" is so much better a term.
I encounter 12oz bottles and cans of 5% abv beer literally every day
One standard drink in the US is tied to 12oz of 5% beer (or it's equivalents in wine/spirits), not the UK definition of a "unit" of alcohol.
When there are US health recommendations made, they are referring to standard drinks.