I believe I read that about the applicators license. The thing is with fresh lumber from the plant, its great to use right away, but its still saturated, its hard to figure even with a pressurized applicator how it will absorb the preservative. If you dry the lumber, smaller dimension does like to warp. Large dimension, timbers and poles maybe not so much.
I can recall how heavy those units of lumber were. We had a delivery one day and the derelict, and or drunk forklift operator, popped a band on a unit of 2x12x16's on the opposite side of the trailer, with one of the forks, releasing most of the lumber onto the driver who was rolling up straps on the other side, and of course it was the top unit, he was crushed and severely injured, nice fresh CCA saturated boards.
There used to be blue and red tags, red was .60 CCA, I remember seeing that in 12"x12", I had bought a cut off from a yard I delivered trusses to.