Canadian code says that if you have a DUI in the U.S. EVER you have to register with the Canadian authorities and you can be excluded from visiting Canada from the U.S.
If that isn't considered bad, I don't know what is.
Whatever. I don't condone what they do. I'm just saying that normally not so bad guys get caught in the system and can't get out. The number of people in U.S. jails is huge.
If you don't understand, you don't understand. It's okay. The U.S. has one of the highest incarceration rates in the world. It doesn't have as much of a social safety net as socialized countries like Canada.