Do you go to the alpine slopes without opening hours?
Outside opening hours, the slopes are a workplace for large machines.
Now it's important that we let the machines work in peace, and don't fool around in the ski resort while these heavy machines are working around the clock.
That way, we avoid disturbing the work, and we avoid exposing ourselves and those who work out there to very dangerous situations. In fact, it's not allowed to be in a ski resort outside opening hours.
Check out this video from Trysil, where they explain a bit about this.