Which one? Python 3.5.x or 3.7.x or something else? Version 3 should be version 3. Anything written in 3 ought to work on every Python 3. Not so in the Python world. And that makes it a mess to use (unless you Dockerize every script).
Perl 5.001 is really old (25 years or so), and lots has changed since then. v5.10 introduced a barrel-full of new features; other important features like the "use v5.10" syntax for supporting older scripts didn't land until much later (v5.16).
Where I work, a few of our legacy systems are still dependent on ~v5.10, which can be a real pain when trying to port code back to legacy. I agree that the Python versioning problem is perhaps more prominent, but Perl 5 doesn't really get a free pass here.
The "use VERSION" syntax is fundamentally much older. It used to strictly just assert a minimum version. It also, pre 5.6, required floating point versions ("use 5.005"). In newer versions of perl, this syntax will also invoke "use feature <stuff new in your version and all versions before>" which allows the use of incompatible new features in its lexical scope. One example is that "use 5.12;" and above will turn on "use strict" in the lexical scope. I fought long and hard for that one. Makes the language strictly better (pun intended).
It strictly does! :) I knew that "use 5.12" implied "use strict" but I didn't know the mechanism, or that it could enable other features as well. That's pretty cool!
Perl documentation online applys to versions of perl that are installed. Python stuff is all bleeding edge - you'll research why something isn't working and after 30 minutes find it's expecting python 3.7.
The whole concept of "virtualenv" gives me an impression of fragility I don't get with perl.
Wanted to use Python 3 for some processing but the Sysadmin said that only Python 2 was available for that distributions version and "didn't want to frankenstein the box"
FreeBSD ships perl5 in base, but python is an addon. I suspect other BSDs may be similar. The only thing more ubiquitous is POSIX compatible /bin/sh but that's much less featureful.
Because of the stability of perl5, I barely care what version of perl5 that ends up being. (Perl 5.10 and up is pretty much what I want, 5.8 and 5.6 are a drag if i might need unicode)
Perl 5 is Perl 5 everywhere.