Implementing the Theory of Constraints requires everybody behave like the Road Runner (the blue bird). It is either running full speed or standing, there is no other option. It should be the same for all our resources, especially the human one.
Cost world, which demands maximal efficiency at every point, leads people into conflicts - conflicts with fellow workers (that don't want to work their hardest ALL the time but don't want to look "bad" either) and conflicts with the system that requires they achieve opposing goals (no over time, on time delivery AND maximum utilization). These conflicts lead people to slow down their pace of work, make sure they look busy (I once saw a shareware that helps cover up the fact you are not really doing anything?) and often times leads them to make the wrong decisions.
Throughput world focuses on global optima, not local optima, and thus accepts the fact that most resources should have idle time. This means that being active isn't always being productive. But to get the most out of the system we need to have all our protection where we need it - at the constraint. Anywhere else it is wasted as it is not protecting the system. Therefore, even though a resource has over capacity and is not constraining the system, once it there is work to be done - it should be done ASAP. Knowing that working hard is not penalized (=rests are allowed when there is no work) should lead everyone to that direction. So there are no conflicts between fellow workers (no one should feel bad or threatened by co-workers working hard when they are not), no conflicts with the system and the road is paved for making the right decisions.