I would doubt that many have had a lot of practice with an auto at low-level.
It is easy to say it is a non-event because the curve says its fine.
Pulling it off over uneven, rugged terrain could be an interesting experience.
Apart from a fear of heights, they fly low because it is cool and creates an experience, not because it is wise to do so
Some times it is wise to do so, Huey formations often flew on the tree tops to make it difficult for the AK-47 carriers to draw a bead. Has to be said though that pilots were not taught autos from such a position. Having said that, the Oz Army taught its Kiowa drivers 360° autos from the cruise on the tree tops, it assumed you had just flown over the only clear area when the noise stopped. This newly minted Huey driver was impressed by the Kiowa when a Bell test pilot was demonstrating it to our military, sat in the back with every seat filled, ultra low level down the strip, throttle chop, climb, auto, touch down, lift into hover and perform a 360° pedal turn.