Re: Safer than a human driver?
To be fair, enforcement of drunk-driving laws is difficult. A great deal of the US is rural and there aren't nearly enough police and other law-enforcement personnel to cover more than a tiny fraction of the roads at any time. Sobriety checkpoints are sometimes useful when there's a high probability of catching some offenders, but they can't screen many drivers – they just don't scale, so you can't have them on busy roads, and on less-traveled roads there are obviously fewer drivers to check.1
Checking for other forms of chemical impairment is worse, because we don't have easy field tests for them and subjective evaluation is horribly inaccurate, a moral hazard for law enforcement, and inevitably widespread violations of civil rights.
And not only can enforcers not easily check for driving while tired – which studies have shown can be as impairing as alcohol – but it's likely to be masked by the adrenaline rush of being confronted by the police in the first place. Driving while tired becomes dangerous when nothing out of the ordinary is happening.
1What about breath-analyzer interlocks? Well, obviously that's another of those hated "tech" solutions. Moreover they don't seem to be hugely effective. New Mexico has had an ignition interlock requirement for anyone convicted of DWI since 2005. Yet there are still plenty of repeat offenses, and some of the drop shown in that report is likely due to COVID-19 shutdowns on drinking establishments.