I think the bigger idea is that people who've never actually written serious code in a dynamically-typed language assume that people who do always write a bunch

I think the bigger idea is that people who've never actually written serious code in a dynamically-typed language assume that people who do always write a bunch of extra unit tests to assert correct types, assert behavior on incorrect types, etc. etc., and that programs crashing due to type errors is a super frequent occurrence. None of those things are true.