That is where the trouble is. The use of SI units is mathematically much easier to apply for most things. The fact that many have used other units for so long is what is hard about converting.
Actually, not just many but most countries have.
People just can't visualize the differences and because of that have a tendency to block it. We are used to buying gasoline by the gallon, change the unit to liters and there will be many confused consumers.
Interesting perspective for that here in UK.
All our road signs are in Imperial units. Miles. My car is set up that way. Service intervals, distance travelled, distance to destination, miles per gallon, average speed....stuff..
But we buy fuel in litres. There are those here who claimed it was a conspiracy theory to obscure fuel price rises.
We are used to things in the construction trades being sized by the foot, yard, or inches.
As were we. I sometimes make things. This I made for my office soon after we moved to this house.
Very basic, I know. Just my office...
Standard materials from your equivalent of Home Depot.
Measurements for the material were given in metric. The depth is
exactly 2 feet.
The milk in the fridge is 2.72 litres. Or four pints.
And, if you order a beer in a pub, it comes in pints.
Despite the move to metrication in UK, we somehow cling on to some imperial units.