I've seen units take casualities when a building rubbles, though not nearly often enough. I guess Paul's answer also covers why units can fire from a burning building and rarely even take suppression.
However, I disagree with it's logic. Here's why.
Troops are trained to take cover, correct? And to seek the best possible cover. So, wouldn't it make sense that a squad in a 'building hex' is, more often than not, in the building? After all, if I recall correctly, ASL uses the same hex size as SP:WAW and it assumes, unless the player says otherwise in the movement phase that the unit in a building hex is in the building. Also, I'd assume that SP:WAW gives cover bonuses for buildings, and, if it does, then we have the assumption, once more, that the virtual men are seeking the cover of the building.
I'm not saying that *all* building collpses or firey buildings should cause casualties. However, more should, especially in multi hex building hexes that are solely building with no other form of terrain in the hex.
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