You don't need klarna for this. Credit cards already fill this need, and with careful use are free. Most people (in my circles) already do this type of thing

Credit cards fill this need for a month of spend, but if you want to go three months at a time you need to figure out a different solution.

When purchasing durable goods or bulk supplies, the difference is minimal. It might require saving before purchase, or gradually moving to the bulk model to preserve cash flow. But it's totally doable with a credit card on the household scale.

That "woth careful use" is carrying a trillion dollar industry on its back, sadly. Clearly society is in fact not careful.

Not really. The people that pay interest on credit cards are the ones that pay for the luxuries/points/rewards of those who use credit cards wisely. If I get a 0% apr credit card for 18 months, i put all of my expenses on it for 16 months. I put that equivalent cash in to a high interest yield savings account (HYSA) and pay the card off before it’s due. I pocket the difference since the bank just gave me a free loan.

I don't think we are disagreeing here, you're just describing the model on why (as usual), the credit card industry punishes the poor or irresponsible. And people who can exploit the system benefit.

I thought the businesses pay it? Isn't it like 3% for a transaction fee that a business has to pay to accept a credit card, and the credit card company gives me the card user back like 1% or 1.5%.

They had a $5 off a $20 purchase promo on eBay recently. I imagine they'd make similar offers on other platforms too.