Cool, now you can pay an attorney $500/hr for them to prompt Astra for 30 minutes, and bill you like they spent the normal 8 hours on the case.

Perhaps, but then someone would do the same but bill you for 7 hours, someone else would undercut them again, until the price reaches a lower equilibrium.

That is an ethics violation. Even in the pre-AI era, getting caught billing for hours not worked was seriously punished.

"7.5 hours - reviewing output"

Sure, if they actually spent 7.5 hours, and it was a reasonable amount of time. If not, perhaps it would be seen as evidence of incompetence.

In the real world, lawyers submit detailed bills and their clients examine them. If you don’t, that’s on you.

How could that be enforced/checked?