It's still measured by wall clock time - not CPU time. I'd love to see them bill for actual CPU time.
Most workloads ALSO hold memory (which is a key constraint) over the entire wall clock time, and the delays and impacts/costs of hibernating out the memory and then bringing it back so you can just be charged for CPU time may not make sense.
Maybe even accounting for strong and weak nuclear forces (not sarcasm...we are engineering at the quantum level now, soon it will be apart of a business metric. Instead of 'equipment' being servers, it might be the domain-space-time used).