No reason to drive while drunk and people who are driving drunk will do so no matter how much public transportation there is just as people who wont drive won't drive even if there was no busses, trains or taxis.
This is pretty unconvincing. I've only driven after drinking alcohol twice, and both of these occasions were in the US (just for the record, I drank only a drink or two). In my home country I've always driven 100% sober, every single time.
Uh, no it's not.
It must be sample bias, but literally nobody in my (quite diverse, both culturally/ethnically as well as geographically) circle of social contacts would consider somebody who drank two beers before driving anything but a hillbilly Cletus (or their countries' local equivalent). The notion that 'virtually every alcohol consuming adult does this' is nonsense.