The difference is that you can bound any macroscopic quantity in fluid dynamics even if you can't solve the equations, however you can't put a bound on iterative processes. Or have economists figured out busy beaver numbers too?

I guess it was only a matter of time before economists stopped misunderstanding physics and started misunderstanding computer science. I mean there's not much prestige left in physics since the end of the cold war. Are we going to see a Turing prize in economics like the Nobel prize?