Even rough sawn is not 2" by 4".

Americans love inventing field specific nomenclature. Like piping sizes, wire sizes, metal sheet thickness, plywood router bit size, construction wood size, furniture/raw wood size, etc

I have always thought it was just a side effect of capitalism. The more messy the units, the harder it is to enter a field without requiring the help of an expert sales.

After 10 months of house renovation it’s my experience that plumbers are the worst offenders when it comes to sizing weirdness.

You think you got the right size fitting, lol nope, it’s actually conical not straight…