This irks me also, more than I'd normally admit. A couple of solutions I discovered over the years; one is to use `hidutil property --set` from the command line for UserKeymappings to overwrite the non us backslash to the backtick (I can't remember the specific codes for the keys, but you can find them online), however, this was cumbersome when occasionally using an external keyboard (I prefer ISO over ANSI) or if you restart the machine.

Eventually I settled on Karabiner Elements, an app that lets you create a simple modification specifically to target the Mac internal keyboard where you can map `non_us_backslash` (that strange unused key) to `grave_accent_and_tilde` which fixes this.