wrt your Spanish example: grammatical gender adds information redundancy to make it easier to process spoken language (e.g. helps with reference resolution). This redundancy enables Spanish speakers to speak at a relatively fast rate without incurring perception errors. English has fewer words but a slower speech rate. It's an optimization problem.
The speech rate issue isn't as obvious if you're only looking at text, but I'd argue/speculate that lossless speech as a language evolutionary constraint has implications for learnability.
tl;dr there is no communication tax, languages are basically equivalent wrt to information rate, they just solved the optimization problem of compactness vs speech rate differently
See also (great read): https://pubmed.ncbi.nlm.nih.gov/31006626/
wrt your Spanish example: grammatical gender adds information redundancy to make it easier to process spoken language (e.g. helps with reference resolution). This redundancy enables Spanish speakers to speak at a relatively fast rate without incurring perception errors. English has fewer words but a slower speech rate. It's an optimization problem.
The speech rate issue isn't as obvious if you're only looking at text, but I'd argue/speculate that lossless speech as a language evolutionary constraint has implications for learnability.
tl;dr there is no communication tax, languages are basically equivalent wrt to information rate, they just solved the optimization problem of compactness vs speech rate differently