The law will, of course, be ineffective to its intended purpose ... but like most with power in the nanny state they’ll feel good about themselves for passing it. Self-esteem is very important to these nannies.
The state likes it because it means revenue from fines.
The lawyers like it because they can drum up more clients/higher rates.
The politicians like it because they can show they are tough on crime (attaining higher office, seeking more contributions).
The insurance companies like it because they can charge higher rates.
If there was no profit motive, they wouldn’t press the issue.
They won’t lock up people because that COSTS the county money. And for some infractions would be considered “excessive”.
BTW blowing below 0.08 does not clear you of being charged, they will sometimes prosecute below that number. Blowing above that number will lead to easier conviction.
There are parts of Alaska that have banned alcohol consumption even at home (not just for criminals, all adults). I heard a pro-pothead cheering about it on Pacifica Radio.