Lou, what you say about Mexican homes, with their thick 'concrete' walls as opposed to NOB stick built homes, is obviously true. But not everyone here is prepared to do what you have done vis a vie ethernet wiring throughout. And you are a 'pro' whereas most folks are neophytes.
I had, in a very large concrete home, good success installing a Google Mesh system. I did take care to place the 3 'slave' cubes as best I could with respect to walls vs the base unit. My speed tests/ping in all portions of that large house are very acceptable.
As always, YMMV