There oughta be a law, for cripes' sake.
Thankfully, it looks like you'll be able to find one soon at the covenance store.
*wink*
As you said, English may not be their first language, so they may not know they've made a mistake.
Why not have a friendly chat to them, point out their mistake, and offer to proofread a couple of their signs and notices?
So there is a sign up saying that there is a new "convenence" store coming to part of the old Chinese restaurant at the end of Academy Street. The very first bit of public notice about a new business, and it is spelled incorrectly. I understand that English is not the first language of many immigrants, and I respect anyone who is bilingual, but for cripes sake ask someone to proofread.