As someone who has lost loved ones to a drunk driver, I can tell you it is not a minor crime.  These "minor" crimes you mention get prosecuted quickly and often because they are open and shut cases where the "beyond the reasonable doubt" standard is far exceeded and even then 90+% of those cases are offered a plea in the name of expediency.  

Also for many people, that argument is also a bit of a deflection that takes away from the impact of "minor" crimes.  Said minor crimes also just happen to coincidentally be the crimes that many of those people have been busted for.  Especially for the "minor" drug charges.  I mean seriously, for several years before MJ was legalized, the vast majority of officers wouldn't pursue a MICS 6 charge if that was a person's sole offense, and that hasn't changed post-legalization even though it's still a valid charge because the MJ law is so narrow in allowed usage.    .