We do have tons of alcohol deaths. But the idea here is that no one dies from alcohol today because their alcohol dealer slips in unknown amounts of toxic potentiators to cut costs (which is effectively what is happening with heroin et al. today).
I don't know any user of any substance that would say "well 1 unit is likely to get me off a bit, so I think I'll take 20 just to be sure".
If alcohol was illegal the death toll might be even higher. People might shift to something with more bang for the buck and have an even shittier and shorter life than dying with 64 from liver failure.