If you are mentally challenged then maybe you shouldn't be given a CC in the first place? If we aren't segregating people and dividing them into groups with certain money handling abilities based on their IQ, we shouldn't be deciding for them.
They are innocent until proven otherwise, right? So they are also capable of making financial decisions until proven otherwise. They were allowed to have a bank account and wire money in there, right? Nobody cared to check if they are smart enough, but when it comes to withdrawing it's suddenly a big deal, because they might do this or that. I can't believe you're in favor of this.
The banks won't loan you any money if you don't have a steady income. Without it the only CC you will be allowed to have is a prepaid one. If they have income they must be mentally capable of handling some degree of responsibility, would you agree?
I think there is some misunderstanding here.
My main point is that people shouldn't blindly invest into whatever asset with money they don't have. In this case I don't see it as a problem that banks are preventing this from happening, because it's their money.
If people, mentally challenged or not, decide to blindly invest into whatever asset with their own money, not a single bank should come in between that. It's people's their own choice and responsibility to burn their money.
Negative aspect with CCs is that people can sign up for one even with state welfare. From the moment they are accepted, which can be done directly via the internet, where depending on the bank, they get instant access to 5000.
In this process, you won't be facing any person asking whether or not it's better for you to not take one because of your low income or mental state. It's a bad way of conducting business from the side of the bank.
If I look at my own bank account, I can increase my credit limit (obviously won't do) to a level where it's 10 times higher than my monthly income, and that with just a few clicks and a digital signature from my banking calculator.