I think the units just don’t make physical sense. Three orders of magnitude between canonical units is just way too much. You always end with either too much precision or too little.
Having worked on Australia building sites I'd like to say that even at distances of 10m you still want to cut with a precision of 1mm. So it's common to hear that cut described as 10,000.
The big jump between units (mm and m) is really useful as even the most preoccupied of coworkers will notice if the scale is out by a thousand. If the units were closer -- say 10x -- then there would be more ordering errors. That explains the absence of centimetres (10mm) from construction sites even though centimetres is a popular household unit.
Millimetres dominates construction as being close to the width of a cut it is the perfect-size unit. It's simple to work with because you simply count: in imperial a tad more than 1⅜" is 1½"; in metric a tad more than 35 is 36.
Even though we retain the same size of timber as in the imperial past, those sizes are now expressed in metric -- common sizes are 90x35, 120x45. So you can measure up an old house for a repair and order in timber of the same size. There are not pre- and post-metric timbers.
That’s interesting about the mm. Most carpenters (having been one) will measure to the 1/16th of inch, rather than the 1/8th. If you’re cutting trim, sometimes you need a bit more precision. There’s a lingo for that, “11 and 5/16 plus a c* hair.” I suppose metric could be useful to move the job site towards political correctness...
For what it’s worth, 1/16” is also about a saw kerf. But in my experience, that doesn’t really matter because, as I was taught, you don’t take the line, but keep the blade completely on the waste side.
