I use no credit card is not considered good grammar. Do not is is morer often used and more proper.
I realize cards is plural but it is a statement rather than i have a credit card singular, we all have more than one.
No, not all the people have credit cards. In Poland most people don't use credit cards but rather debit cards.
Also I'd guess that most people don't understand the difference. I didn't, actually. I would automatically call my card "karta kredytowa" without giving it any thought, and now I know that I would be wrong. Also I imagine that many people who actually understand the difference, still use the name 'karta kredytowa' for the debit card... although I may be wrong. I have almost zero knowledge about such stuff.
Also: why the heck would someone spend money they don't have?
And as the grammar is concerned, I'm afraid we're going to stick to the singular thing.
On the grammar, l don't see the reason this can't mean "I don't use credit cards", which is somthing that might be said in English, and karty appears to be plural. Are previous messages on the subject missing?
This can't be plural, because it's singular. As most feminine nouns, "karta" has identical forms for: Genitive singular, Nominative plural, Accusative plural. And "kredytowej" is undoubtedly singular.
Those are terrible to me, you can have someone steal your card and clean your account, on credit, you are liable for only fifty dollars if that and you can stop payment if you feel scammed. Having sold my business four years ago I use the credit card for the protection and convenience and pay it off full at the end of the month, not a cent in fees in three years. I bank my money there and I'll be darned if I will pay to use it while they make a profit loaning it to others. We Polish people are too smart for that.
"my" was just an option - in Polish the possessive pronoun is often obvious, in English not. But frankly, this sentence seems too general to me for 'my credit card'. Deleted this option.