[SXX]

Yeah, I get that regular expressions might look complex and tangled like brainfuck looks for me since I never tried to learn it. Yet I just see comments on how regular expressions are hard to understand from all kind of IT people who solving hundred times more complex puzzles every day. I guess it's just reputation that stick to certain technology and really have nothing to do with actual complexity.

[hatch_q]

Experience i guess. I've spent hundreds of hours on debugging and fixing regexes that other people wrote - usually just to find there's a quirk in certain regex parser implementation.

Regexes are easy to understand if you write them, but reading them can take lots of time.