Python

All of these can be done with raw strings just fine.

For the first pathlib bug case, PATH-like lookup is common, not just for binaries but also data and conf files. If users explicitly request ./foo they will be very upset if your program instead looks at /defaultpath/foo. Also, God forbid you dare pass a Path("./--help") to some program. If you're using os.path.dirname this works just fine.

For the second pathlib bug case, dir/ is often written so that you'll cause explicit errors if there's a file by that name. Also there are programs like rsync where the trailing slash outright changes the meaning of the command. Again, os.path APIs give you the correct result.

For the article mistake, backslash is a perfectly legal character in non-Windows filenames and should not be treated as a directory component separator. Thankfully, pathlib doesn't make this mistake at least. OTOH, / is reasonable to treat as a directory component separator on Windows (and some native APIs already handle it, though normalization is always a problem).

I also just found that the pathlib.Path constructor ignores extra kwargs. But Python has never bothered much with safety anyway, and this minor compared to the outright bugs the other issues cause.