I suppose it depends on your definition of 'expensive'. By that I mean, if your computational model is inherently serialised, sure, regexes are cheap. If fuzzy matching and rough temporal correlation between processing units turns out to be cheap, perhaps regexes are ridiculous extravagance on your hardware family.

I suppose you could turn it around - assuming our language processing is optimal (bit of a leap) you can infer things about our hardware architecture by the languages which we parse efficiently.