He played on the chance of in a place known for it. Most of this land is wild and not the 21st cen where there is little unmanaged land.
Modern avalance prevention is just that. Prevention. Meaning they cause a avalance before it can occur naturally or to ease snow loads. So, in order tontrigger one they either drop dynamite or other impact based explosive or use large artillery to prematurely drop the accumulated snow before it becomes a risk. If the snow is ready to slide just a barking dog or person speaking can set it off in the right circumstance.