I'll bet that if you talk to designers and road layout experts, they'll freely talk about the "language of traffic signs". I'd also hazard a guess that people who are not programmers or familiar with how it all works would not refer to what we work with as a language, but as "code", "mathematics", "bits and bytes" etc.

The numerical-analysis community refers to software as "codes" :-)

I have recently seen a SIAM book that even had it in the title.