Laser wont work on fields that aren't flat. If the ball is spotted on the far hash the laser won't make it.
They could have the laser elevated a little bit. I dont think the fall off is more than 1/2 foot or so. Or they could put them on either side with a slightly up angle.
Exactly. It would be a simple answer, and it would speed the game progress (instead of awaiting the fat guys running out with a tangled chain).