It has honestly been well over a decade since I last touched Perl (not that I'd mind going back to it), so I can't say much to most of your specific criticisms.

But, evaluating true and false in expressions is tricky in a lot of languages now. PHP is notorious for it. That's why you shouldn't mix data types. Regular expressions are no longer the sole domain of the Perl hacker, they're a regular staple of JavaScript and PHP and the commandline and other utilities.

Look, here's the thing: the response to avar has pretty much been, "you guys are doing it wrong", which is a seriously uncool armchair quarterback thing to say to someone else, especially someone that's a part of something as big as booking.com. If in fact their hiring process was as unutterably broken as you seem to believe it is, wouldn't you've expected their business to collapse in a pile of inscrutable bugs by now?

I'll readily agree that there's a vast difference between a coder in any particular language, and an expert in that language. That's why the experts get to define the language conventions used by a business, and the coders get to follow them. That's why there's testing and debugging and staging.

I try to assume least level of incompetence in other people on HN. Maybe instead of declaring things about their code base that you have no actual knowledge of ("There's no way anyone can just pick up Perl and write good Perl code without a dozen best practice errors. Hiring someone who doesn't know Perl very well basically guarantees a high rate of bugs in your codebase."), you could instead ask, "How do you guys handle training the guys that aren't very familiar with Perl quirks like int@_ vs $#_?"