The problem with any "per query" cost is that it's inherently scary due to it's unpredictability - founders end up worrying about covering costs if they grow faster than they can build revenue. Using a service that charges a fixed, predictable amount is more attractive because you can sign up and just forget about it (to an extent).

There could be another company that is in the business of risk management. It could sell unlimited or quotad amounts of api calls for a fixed price. There is no reason for these two to be the same company.

Total hogwash! It's super scary. Variable costs are something you keep to an absolute minimum in a business. A fixed price API (at least for a certain number of calls) is attractive precisely because it is not taking a chunk off your top line.

You want fixed costs to be low as well, but at least your revenue can grow independently so marginal costs decrease with each additional dollar you earn.

> It could sell unlimited or quotad amounts of api calls for a fixed price.

If you are an API provider, it is a great deal to offer fixed pricing. First, you have a more predictable line of revenue. Second, if you are a small player, you are not as exposed to fluctuations in demand. For the latter case, that means you don't need a lot of cash on hand to even out cash flow issues.

> There is no reason for these two to be the same company.

This is a classic middleman business. As the API provider, you need to make sure this does not happen, unless you are having serious sales problems. You'll just get the squeeze as the middleman eats your margin.

Pretty sure you are thinking of variable pricing. Variable costs are different. From Wikipedia: "Variable costs are costs that change in proportion to the good or service that a business produces." https://en.wikipedia.org/wiki/Variable_cost

Say you created an API that takes users' data and stores it on S3. Some random user then comes, pays you $10k to store his data, but a week later does a chargeback. You're left to pay the costs to AWS.

Finally, with CCs you need to strike deals with payment processors like Braintree. If you're a private developer it will be impossible. But even as a company - payment processors are not ready to process payments via command line. They will ask you where your terms of service are, what's your website, what's your refund policy and so on.

The threat of chargebacks disciplines the market to provide reasonable customer service.

These models turn existing models on their heads, so be aware of other pitfalls. Productive paranoia is good, but only practice it after you innovate first.