Native speaker here, and recently I got into a discussion with my pops about the word 'signage'. His contention is that the word 'signage' is entirely superfluous and is only used as a $5 alternative to the word 'signs'. My contention is that there may be (maybe not, too) a valid reason for using signage instead of signs.
According to Merriam-Webster, the word signage was first seen in 1976, which makes me think he may be correct - after all, if it were grammatically correct, one would think it would have appeared alongside the word signs.
If it is grammatically correct, why would signage have taken so long to appear? Is there something inherently different in how we think about our signs in modern times?