Last time I was at a concert in San Francisco Bill Graham auditorium, I noticed that lasers travelled fixed path always pointing at the walls or between balcony levels, never at people.
See the comment below regarding concerns of misalignment, limit stops & containment for beams with the power to cause permanent blindness. I'm sure some venues handle this safely [1], but powerful lasers are being treated far to casually for my liking.
[1] Though I wonder what would happen if you asked for a copy of their risk assessment?