> If a job listing asks for Python and someone submits a resume that does not list Python, it's fair to reject that candidate.

The thing though is it's a bad requirement. There are any number of great candidates who could be proficient in Python - the skills are very transferrable. (It's like trying to find a painter and filtering out people who have never painted a brown houses)

The thing you're screening for by being so specific is not finding the most qualified person, you're going to end up with the person with the most time and patience to fib or lie on their resume.

> I doubt the "best candidate" is also the person who can't be bothered to take 10 minutes to update their resume before pressing submit.

That's exactly wrong - the best candidates are going to be busy people who are great at their job - the people jumping through HR hoops to get hired are by nature going to be worse candidates.

So, I recently got about 600 resumes for a senior Python backend position.

Out of those about half had no experience in backend or python, plus weren't senior enough for us to consider. Or forgot to include all that in their CV. They get filtered out in the first filter phase.

While I'm sure a portion of those could do the job, I can't realistically interview those 300 people when there are other 300 who happen to have at least written that in their CV.