Could an engineer come up with a cheap and ready means to prevent these deaths, via supports? Sure. I doubt it'll ever happen.
How many roofers do you know who will use or require use of some sort of rescue mechanism when they build on a roof? I never understood why they're up there with no net, no cable, nothing...It always seemed that it'd be so easy to design some protection for these men.
For the most part, falls from heights are only considered life-threatening when the elevation is above 16 feet; the problem about houses lies in the sharp-cornered obstructions along the path. O.S.H.A. rules are available free upon request; understanding them and implementing them requires a bit of expertise.