It's really sad that this is the case, but in the lab I worked for at a UC many of our costs were complete BS made up so that we could use up the full amount of our grant. The system encourages this behavior. The logic is completely flawed: If you don't use the money, then you obviously don't need it. Next time you won't receive the full amount from your grant. When your grant is millions of dollars over a few years, you end up having a lot of very nice dinners paid for with money that was meant to be used for research and education.