1. No one except that person would be able to write, so there would be no one to manage the newspaper.
2. Road signs would be an issue (car accidents, etc)
3. No one would get their mail, unless the person that can read was the only mailman for the whole town.
4. Even then, the mail couldn’t be sorted unless there were machines to do it.
5. No one would be able to work at restaurants, so no one would be able to go out to eat.
6. There would be no companies in town if no one could read, because you need to read and write to be able to create power bill, water bill, etc
7. The person that can read may be a liar and could convince the whole town that something important was written (law, etc) even if it wasn’t.
8. No one would be able to work at a pharmacy, and no would would be able to read their directions anyway on prescription bottles.
9. There would be no schools for children.
10. Church would be non existent.