They're not only shone from directly below.
How much ground can you see while sat in the cockpit? A laser in that area will hit your eyes directly. I've been hit, and it's not my idea of fun. I definitely didn't want to look for anything in that direction, which could pose a problem.
Owning those lasers should be equalised with owning a weapon, and as there are no permits it'd be owning an illegal weapon. Couple of months free food and lodging should be the minimum for pointing one at aircraft.
Right now, they're getting a slap on the wrist in my neck of the woods. Probable effect: Nil. As usual, it will take accidents before someone decides to actually do something about it.