I disagree entirely, I understood it as "no women were allowed to have a bank account anywhere in America before 1974" and I guarantee I'm not the only one. The very existence of this discussion thread proves your statement wrong.

I don't think that's the point in dispute, but that's not what the quoted post is saying.

"Women weren't allowed to open a bank account in the USA until 1974" implies that, until the year 1974, there were no women in the US who had opened bank accounts.

The more accurate statement would be "The right for women in the US to open bank accounts wasn't nationally established until 1974," which aligns with the reality wherein many American women were still able to open bank accounts before then.

That's not what was said, though. "Some banks weren't legally required to let women open bank accounts" is a very different statement than "women couldn't open bank accounts."