not really:
yours and my npub have a bunch of history; it would land well within the range of acceptable risk for a service provider to spend, say, 1000 sats of cost to process data for a, say, 10k sats reward when the service provider doesn't have any kind of data on our npubs' behavior wrt paying for data processing
this should cover 99% of the use cases while keeping the mechanism incredibly simple, and for new/disposable npubs, service providers can coordinate some form of prepayment; but this approach allows us to keep the happy path super simple
(pushing risk to service providers who are able to price it)