I'd don't know where you live but it's not the UK I recognize.
In the UK we sell most drinks in litres or millilitres, and I would prefer to get milk that way too. Beer is an exception but when in Japan I don't find buying it by the litre at all burdensome.
Ingredients in recipes are mostly metric now, or use both units. I always use metric because like anyone else who went to school in the last 40 years I never bothered to learn Imperial measures.
I measure my height in centimetres, always have done. Clearances for vehicles are given in metric, not least because foreign drivers from the continent wouldn't have a clue otherwise.
I ask what the fuel economy is in l/100km, or more often just read it off the spec sheet attached to the car in the showroom. It's a more useful metric than MPG, and besides which fuel is sold in litres. Wood is sold in metric units, e.g. the last bit I bought was a 1200x600mm sheet of plywood.
The weather reports on TV are in Celsius, and it's becoming less and less common for them to bother reporting Fahrenheit. In fact the only people who do are low quality newspapers, and I never have a clue what they are on about when their front pages scream "90F HEATWAVE!"