I'm wondering if "Master" isn't the problem — it's "Slave" that's not so good. And, when changing "Slave" to e.g. "Follower", it makes sense to rename "Master"

I'm wondering if "Master" isn't the problem — it's "Slave" that's not so good. And, when changing "Slave" to e.g. "Follower", it makes sense to rename "Master" to "Leader" too. I'm surprised some people want to rename the Git "master" branches to "main", although the word "slave" is absent in this context. That's similar to your MasterCard example? (Rename to "MainCard".) But I'm not a native speaker or color minority person where I am currently, so what do I know. At the same time, "main branch" is shorter than "master branch" and simpler to understand for beginners? I think it's a better name.