Agree, even in the payments space usage-billing metrics providers like Chargebee / Lago etc get order(s) of magnitude more data than payment.

Granted payments and associated ledges require a level of consistency that other systems do not require, but that is orthogonal to high volume.

You'd be surprised how antiquainted many of them are. I don't mean Stripe or Braintree but the long tail of terrible terrible credit card processors. If I hear "Chase Payment Gateway" I shudder.