I once saw a pitch for Google VC by a company selling mandated breathalyzer ignition locks - and insurance. The founders were a criminal lawyer and an insurance salesman (brothers). Their angle was to get state legislation passed, and win per-state government monopolies on the interlocks - and then cross-market auto insurance to drivers who had to buy the interlocks, because most carriers won't insure drivers after a DUI.

It was the creepiest, most cynical thing I've ever seen.

Those guys are gonna be RICH.

And then we add a mandatory breathalyzer check to the remote VPN login. Because if people believe they can still drive, they might just believe they can still answer the pager.

Every time I've seen them discussed, I see brought up that they're not especially reliable.

Denying transport to someone who's got a history of doing anti-social things behind the wheel seems reasonable. But making them required for all vehicles (if I'm understanding your intention correctly) seems likely to have undesirable results.

Breath tests are notoriously unreliable/inaccurate, to such a degree that in some jurisdictions the law is now phrased entirely in terms of a machine reading since it's been established there's no reliable relationship between the machine reading and blood alcohol level.

Seriously, read up on the history of breath-test machines sometime. Everything from difficult chemistry to literal "oops we misplaced a decimal point in the software".

They're very expensive and they're not especially reliable.

There were a few guys at the bar I used to hang out at that had several DUIs, had the ignition lock, yet somehow seemed to get on the road after closing the bar.