Not a fair comparison. Unlike shoemaker or coopers who do ONE thing, a SWE doesnt do just one thing.. atleast in general. I churned through basic, logo, c, c++, java, c#, python, go and now agents. The executable building on single machine died when distributed systems came in. It again evolved when cloud took over. We have been reinventing our work every few years. Every job change requires us to learn new skills.
How much did a horse farrier have to learn if they switched their employers?
No profession uses only one skill. I’ve had a few, the longest-running as a developer, and there is nothing uniquely varied about working in software. One thing that is pretty unique to software is how superior they feel to most other professionals, when in reality, it’s a pretty mediocre discipline compared to electrical or mechanical engineering, medicine, chemistry…
Cobblers design, make and repair shoes of various kinds, boots for various purposes, slippers and moccasins with leather, cloth, rubber, and many kinds of threads using punches, knives, various machines, glues…
How much does a developer need to learn about their core competency when switching employers? Not even close to as much as a machinist. It’s not a useful comparison.