After seeing the shoddy workmanship on the new houses being built in my neighborhood, I am tempted to say that nothing could reduce the chances that a carpenter will make an error. Few of the construction workers can measure or cut a board the the right length. (Few can speak English, either—but that is another issue.)
Not that it matters much: If the board is too long, it can be forced to fit; if too short, it can be shimmed. If the wall bows, the drywall people can cover it up.
Fortunately, carpenters don't have to carry out complicated calculations, so it probably doesn't matter much which system of units they use.
You don’t do much carpentry work, I take it.
I am sorry you have had such problems with carpenters. Most of the carpenters I know are salt-of-the-Earth types, and real craftsmen.
Has it occured to you, BTW, that most of those non-English speaking carpenters you malign were brought up learning the Metric system? Is it any wonder they can’t do a decent job?