Unix glob allows the wildcards to be escaped with a backslash, but glob2rx doesn't. This matters for filenames which contain a literal '*', '?', or other glob wildcard.
Assuming a directory structure like:
> system('ls testdir/\\*.txt')
> list.files(path='testdir', glob2rx('\\*.txt'))
As expected, glob2rx incorrectly treats this '*' as a wildcard:
Although the docs note that glob2rx may not work with arbitrary characters in the pattern, this kind incompatibility might still be unexpected. For example, a naive use of glob2rx on filepaths would allow wildcards to match '/', which glob does not.