I'm not sure. I know in a lot of those places, the rationale is that the terrain is too flat, so rifle bullets can travel too far.

The problem is that I don't know if that actually corresponds to increased risk of death. It sounds plausible, but idk if there are real stats to back it up.

A quick search for some plausible data turned up California's official stats, and going back a few years, I never saw more than 5 deaths in a year. Extrapolating the rate to the whole US, that's like 50 per year. Other sources just say "less than 100 per year for the whole US".

Without a specific study, it's just as plausible to attribute the fatalities to sheer proximity of the shooter to the victim rather than bullets traveling far. Bigger targets are easier to hit. Just looking at the California data, which includes injuries, this seems to bear out, and most injuries and fatalities are due to close range shotgun bird hunting (i.e. the Dick Cheney).

And really, if you wanted to completely eliminate the risk of rifle bullets traveling further than intended, you could mandate the use of any elevated shooting position (which some places do for archery).