to be fair, im not sure its a conscious choice, since its not really easy to couple lets say data transfer bytes directly to billing data in real time, and im sure that would also use up a lot of resources.

But of course, the incentive to optimize this is not there.

AWS already does per hour billing for spot instances.

I mean, generally real time isn't needed. Even hourly updates could save a massive amount of headache. 24 hours or more is becoming excessive.