No. it explains this:

I’m not American, but I’m really surprised that some Americans don’t know anything about Spanish.

having a lot of Latinos in one place doesn't mean there's a lot elsewhere, or that the people who made the sign are even anywhere close to familiar with any sort of Latino culture... for example, in Minnesota, there's a large number of Puerto Ricans in St Paul. if you drove forty minutes out west, you're not going to see that. Same goes with the Somali influence in Cedar Riverside, or the Hmong neighborhoods.

as for the sign... the people who actually made the sign don't give a flying rat's ass what's on it. A client sends them a picture or something, they print it, and send it out. If anyone even actually looked at it. It could have been an entirely automated service like vistaprint or whoever.

its like the bakers that put "just say 'Happy Birthday' in rainbow icing letters" on the cake. they're not paid enough to care what they're actually printing.

Which means the only people who probably who really needed to fail to understand the distinction is... the people that ordered it. And when you're talking about somebody who probably hung that up on their fence... there's not a "chain" of people involved.