I don't know what the right term is, but maybe "deterministic" pricing (this is not the right term, but maybe closer). That is, I'm not going to know how much a sprite cost until I see the bill (or look up the live usage report), whereas if I spin up a Fly Machine, I know exactly how much I'm going to pay per unit of time.
(Both make sense for their respective use cases.)
Ah, that makes sense. Yeah, that's a technical limitation! I'm sure we'll work through it at some point this year, but it's a consequence of the fact that for most people, most of their Sprites are dormant most of the time; it's how you comfortably get to having 20-30 Sprites (making a new one any time you do something new) for every user.
It's a good callout, a genuine difference between Sprites and Fly Machines. Believe it or not, it's intended to make Sprites cheaper than Machines.
I absolutely believe it! And feel the pricing model makes perfect sense for the use case.