Well, yes, I'd they know that texts have an encoding, how to detect it, and what functions to call to convert between them, I agree they don't need to understand how they actually work.

That said, I think the "we work in English" is a mistaken belief. Clients, employees, products, suppliers, etc, all will have names with non-ASCII characters.

My name is André; send me a letter or email with my name garbled, and I will mock your company publicly and, if you are a tech company, heavily consider dropping you for incompetence.