Arithmetic continues to work even if you don't use metric units.

Construction and civil engineering (in the USA) is still done in feet and inches. All construction materials are sold this way. It would just introduce error to try to plan a building in metric dimensions.

"Eschew flamebait. Avoid unrelated controversies and generic tangents."

https://news.ycombinator.com/newsguidelines.html

If the piers are sold in inches, then using metric to describe them is another level of indirection, so might make the chance of error worse. Would you feel safer if he said "The piers are 91.4cm"?

It's amusing to see newspaper stories where they report high precision numbers that are obviously metric conversions like "He drove 62.14 miles to work every day" when the original source said "100km".

The construction tradespeople only use imperial. The engineers could use metric, but then they would have to convert everything. It’s easier to just use imperial from beginning to end. Besides, all construction materials are in imperial. It is so much simpler for the engineers to use imperial. Plus, if they grew up in the USA, the engineers are as comfortable using imperial as you are using Metric.

America. I had to mentally switch to metric when I moved to Europe and now I have to switch back. Ugh.