[mcswell]

"If language processing has a universal basis, why all the confusing variety..." Because the universal processing mechanism provides lots of options for individual languages--the option for different words, obviously, but the option to use or not to use morphology (and lots of varieties of morphology), and different syntax rules, etc. etc.

To use an analogy, a computer chip provides a single instruction set at the machine language level--yet you can run a huge variety of computer languages on it: FORTRAN, LISP, Python, Prolog and so forth.