We have a notorious question in one of our coding interviews, designed to weed out people who've slapped 'Postgres' on their CV (because that's what we're looking for) when what they really mean is "I've used MySQL a lot, and it's basically the same, right?". People get choked on that about 70% of the time.

If you put something technical on your CV, be prepared to be tested on it in a coding interview!

Not sure I agree with this approach. Most job postings are a smorgasbord of bullshit that list a bunch of things the employer doesn't want on the posting either do to managerial ignorance, recruiter butchery or targeting cheap import labor who view checking the box as a matter of course. So yeah, if someone wants to be filtered by software and never get a call back ever they can feel free to leave something off for the sake of puritanical accuracy.

At an engineer level, if someone admits to cursory postgres knowledge and confers a strong background in SQL or Oracle, I'll assess base knowledge on those platforms understanding most of the specifics are easily taught. The significant differences are closer to dba level and aren't at the level of abstractions devs would be working at anyways. The specific provider of the data persistence mechanism is generally of marginal importance and is subject to replacement in most projects of any size.