Since our friendly friend is in Canada, my guess is because 28:1 has a nice easy formula to remember of 150 mils per 4 liters of gas.
Canada switched to metric in 1976 when I was 21, but the railroad (railway in Canada) where I spent 42 years and 12,000 shifts is Imperial measure. Then add US fluids in gallons, quarts, pints and fifths and I'm forever doing calculations in my head.
My daughter who never finished high school (neither did I) is an OB RN and in charge of the charge nurses, measures everything in micrograms. (one thousandth of a gram) Especially when administering the new classes of pain killers.
Now add firearms; Bullet weights and powder charge weights are in grains, which is 1/7000th of a pound because there's 7,000 grains of flax in one pound. Bullet energy is expressed in foot pounds in North America, which is loosely based on MC2. Speed squared X bullet weight divided by 45 gets me close. 7.62X 51 is a Winchester .308" X 2" case, as one inch = 25.4mm. Sometimes barrels are measured land to land and sometimes groove to groove.
The 105mm is a 4 inch gun in the old money and the 155mm a 6 inch gun. Because of NATO we had to learn the metric system.
"Brad, what do they call a quarter pounder in France?"
Tire measurements are a hybrid. My 285/75R18s = (11.22" X 1.5 + 18)= 34.83" OD if the tread is 16/32s (12.7mm) or half an inch deep when new.
100kms x .62 = 62 miles. The Canadian dollar value is 62% x USD, and our taxes are 62% higher.
20C is warm enough for me to mow the lawn in Daisy Dukes. Minus 40C is minus 40F. 0C is freezing and 100C is boiling.
Because of the metric system, I have two sets of tools. Some old English motorcycles have some odd ball nut and bolt sizes.
Water reservoirs are measured in acre feet in USA, Canadian lakes in cubic kilometers and rivers flow in M3/s.
Whisky is Canada (80 proof or 40% by volume) is sold; 12 oz is a Mickey, 26 oz is a 26er and a 40 oz bottle is a 40 pounder.
Maybe because it takes 3 days to pounder down.
Party became a verb in 1969.
Ripcord; I went the other way. 2x200 ml bottles (400ml oil) x28= 11.2L gasoline. I don't like to pre-mix too much at a time. Only what I can use up in a couple of months.
