[jltsiren]

There is a difference in the required granularity.

Today there are usually only a handful of overhead rates for the entire university. Accounting only needs to be precise enough to attribute the spending to the right categories. Nobody needs to know which departments or labs benefit from that particular spending.

But if everything needs to be attributed not just to a specific department and a lab, but to a specific grant, things get complicated. Maybe one lab in a department only uses offices and meeting rooms. Another runs a bunch of servers somewhere on the premises. And a third has a wetlab and works with hazardous materials. Sometimes things go wrong and the entire building needs to be evacuated. Which means there is a need for all kinds of protocols and trainings and responsible personnel. And maybe also for more security guards at night.

Expect fun department politics when the PIs argue who needs to pay what for the infrastructure and who gets to spend more on actual research.