Why do you assume that all developers have studied CS?

Most developers have never even heard of lambda calculus.

i wouldn't say that lambda calculus or turing machines have ever been part of my programming toolkit (i do know what they are), and i wouldn't expect say a new programming hire to know much at all about them. FSAs are a bit more useful, but you can get an awful lot of development work done without direct knowledge of them.

I got a bachelor's in CS and never learned lambda calculus.

Same. Turing machines and FSA yes, lambda calculus no.

Nope, I'd say 90% of developers globally would not know lambda calculus. And in non-functional languages when was the last time you had to consider the differences between Beta and Eta conversions/reductions when writing a Django SaaS? Or a Java Swing GUI?

Software engineering != Computer science

Lambda calculus is not a required class in my university in either CompEng or CompSci..

Formal theory of computation (finite state automata etc.) was also a higher level elective that depended on your concentration.