I've gotten so tired of having this argument. Inevitably some clerk will insist on calling me by my first name, "you know, your legal name". No. My middle name is my legal name. It's what my mom, sisters, wife, friends, teachers, coworkers, doctors, and everyone else call me. My first name is an aka at best, except the only people who insist on using it are ones wrong about the law, so I'm not even really "known as" it.
I once closed a bank account 10 minutes after opening it because they insisted that my debit card be printed as "Joe Smith", not "Frank Smith". I told them I'd absolutely refuse to touch it because that's not my name. I find it interesting that it's mostly local orgs who are a pain in the neck about being wrong about this. You'd think a small local bank would know local law better than a huge multi-national, but the giant bank I opened a business account with was totally fine putting Frank Smith on my accounts. Go figure.
(Somewhat related: That's made me super sympathetic to trans people who want to be known as something other than what's written on their birth certificate. Yeah, I get it. It's nails on a chalkboard when someone calls me Joe, so if you don't want people calling you Tammy anymore, I'm on your side.)