There are a frightening number of systems that don’t allow “-”, which isn’t even an edge case. A lot of people - mostly women - hyphenate their last names on marriage, rather than throw their old name away. My wife did. She legally changed her name when she came of age, and when we met and married years later she said, “I paid for money for my name; I’m not letting it go.” (Note: I wasn’t pressuring her to take my name.) So she hyphenated it, and has come to regret the decision. She says she should have switched, or not, but the hyphen causes problems everywhere. It’s not a legal character in a lot of systems, including some government systems.