Years ago, the Washington State Ferry system tried a measurement rule on the passenger boat, using aviation standards of an 18 inch wide seat.
One can only imagine the the issues at ticketing with an 18 wide gage. Public outcry, ACLU involvement, and other issues that happened...needless to say, that stopped very quickly
I would note that ANZ has a very strict carryon weight limit of 7 kilos. This causes all kinds of problems for people, but in reality, I think it is a very good idea.
People have enough problems with the body scanners, can you imagine trying to weigh them??