> ... our refusal is based on emotion and familiarity ...
Not true!!!
Our resistance to metric adoption is based on the requirement that businesses would be required to retool and change all of their manufacturing equipment to metric. This would cost billions of dollars.
Our decision to stay with inches, feet, pounds, ounces and gallons is based on economics.
I'm neither for or against metric. I prefer standard. However, I've been working on cars as a hobby since I was 12. Everything I've worked on from the 80s forward has had metric bolts/nuts. Some in a mix of metric/standard, some all metric.