> 2) the confluence of meteorological circumstances needed to generate a lot of tornadoes (and therefore a larger population of very destructive tornadoes) just aren't present anywhere else in the world.

This is in fact a huge part of our tornado risk in the US. The long north-south region of mountainous/high elevation (i.e. the rockies) going into a large low elevation flat region, helps create the 'layering' of different air temperatures that cause tornadoes once the current changes enough for the top/bottom layer to turn into a column.