I think for me it comes down to being able to tell what people want to be called, and we expect our children to name people as they indicated they'd like to be named. At the medical practice we use the Drs generally introduce themselves to kids as "Hi there, I'm Dr. Firstname", to Adults they'll say "Hi Firstname, I'm Firstname Surname." If they're using my first name and not using their title I'm not going to. Specialists from previous generation "Hi Mrs Surname, I'm Dr/Mr/Proff Surname" gets calle whatever they name themselves...

And I know my kids are completely able to refer to the same adult by up to three titles based on context with no crossover and difficulty... At a previous school all female teachers were Miss Surname, married or not (I have NO idea why), so teachers known outside of school were Firstname in social setting, Mrs Surname in certain settings and Miss Surname at school...

I have no investment in being called mum or not, my husband and I both talk about each other as both Mum/Dad or by name and I honestly don't even notice what my kids call me as long as they speak respectfully to me. Mum, Mama, Mummy, Firstname... They're all me... I'm pretty sure none of them are using my first name much at the moment by I can't honestly remember because it doesn't register.