Yes I have a hard time understanding that perspective as well. If someone opens a business in my city and doesn't speak enough English (or Spanish) to complete a business transaction, I just wouldn't do business with them, and it'd be their loss not mine. The only way it would irritate me is if an essential business like the grocery store was completely staffed with people who don't speak a language I understand. In that case I don't have much an option to not to business with them.

I think a lot of people in countries like the US get worked up when people speak a language they don't understand because they feel excluded. And somehow it's vaguely threatening to have people talking and you are specifically cut out of the conversation.