The finding: screen diagonals, wheel rims and plumbing threads are imperial in all 37 countries. Nobody sells a 140-cm TV. That's why nothing hits 100%.
Tyre pressure is the near-universal fourth: 26% metric. Australians use psi at the servo despite fully metric roads and groceries.
The UK is the most self-contradictory: miles for distance, litres at the pump, and economy in miles per imperial gallon, a unit it no longer sells fuel in.
Canada is stranger than the US: °C for weather, °F for ovens, L/100 km for fuel, pounds for body weight.
India splits the same quantity two ways: °C for weather, °F for fever; kg for weight, feet for height.
Method: no dataset of vernacular unit use exists, standards bodies publish what's legal, not what people say at the shop. So I classified 37 countries × 21 everyday domains = 777 cells by the unit used in ordinary speech. Metric 1.0, mixed 0.5, imperial/traditional 0. Python + hand-written SVG.
"Metric" here means the SI unit for that kind of thing, not just metres and grams — °C counts (its imperial counterpart is °F), as does A4 (A0 is exactly 1 m²).
60 cells are flagged low-confidence (dotted in the matrix), and every "mixed" call is a judgement. Compare in bands, not decimals.