It feels like Tesla's pitch for it's current iteration of self driving is that it is akin to spotting someone who is lifting weights. Sure you are paying attention the entire time, but it's much less demanding that lifting the weight yourself. However to me it's more like if you were spotting the spotter. Most of the time you can get away with just being on your phone or zoning out, but to do it right you basically have to spend the same amount of energy as the primary spotter.