Why do Braizeiros NEVER under a question like this:

Há chá aqui?
Há wifi aqui?
Há alguma mesa livre aqui?

Never. Never. Never.

I’m aware of tem ... ?. I’m aware that I could ask vende-se ...?. But Há [...] aqui? is a valid, normal, simple Portuguese phrase which must be understood ANYONE who speaks it.

What’s the matter?