This is a straw man argument, because only relative terms matter. Nobody cares about the absolute numbers except your boss. The customers care about their percentage chance of encountering spam and fake reviews.
You're saying it's too hard to achieve 100% success (0% failure rate), and that we should settle for 99.999% success (0.001% failure rate). Multiplying these by big numbers is irrelevant. It could be a trillion. Who cares? The implication is that the system is nearly perfect.
Meanwhile the experience most online shopping users have is more like a 80% success and a 20% failure rate at best, and often more like a 99% failure rate and a 1% success rate for regular shoppers. I have personally long since given up on every buying anything from EBay or Amazon because of the rampant fakery. Literally everything has a thousand AAAA++++++ reviews that all are obviously generated via a template.
The same argument applies for Medicare: The citizens don't care about the absolute budget, they just care about their individual tax increase or decrease. Only a handful of people in the treasury care about the absolute numbers.