Accrual accounting was adopted only about eight years ago. Before that we had cash accounting.
Accrual accounting was adopted, and then there were a great number of complaints from senators, as they couldn't follow the accrual accounts. As a result, the estimates began to creep back to a cash basis.
There is talk at the moment of going back completely to cash accounting. That hasn't happened so far, but there has certainly been talk that it's being contemplated.