watched the video again. at about 1:43, notice the hand signals when the guy in the red kayak gets stuck. it looks to me as though they have a “ground crew” tracking their progress through there. that would be a very good idea. strong labor unions, it would be difficult to lower their pay. with the tenure system, it would be difficult to let them go. if they were let go, they would be difficult to replace. the likely result would be an increase in class sizes. 