In Perl's case that was quite intentional.

Larry Wall used grep over a Usenet feed to be sure that he would catch all references to Perl. (He did this before Kibo popularized the technique.) He therefore wanted a name that (among other things) would have very few false positives.

Worse still: J, K, R, Io, T. At least with Python and Ruby, you can google for "python programming" or "ruby programming".

Also, some forums don't allow you to search for single-letter names.

Ummmm, C?

True, but C's past the critical mass where googling for just "C" is likely to get you info about the programming language. 3 of the top 10 results (including #2) are about C programming. Most of the rest are about Citigroup, which has the stock symbol 'C'. (Oddly, Cookie Monster is missing.)