That's the real problem. Cops are actually pretty good at catching drunk drivers, but once they catch them and get a conviction, the penalties aren't all that severe. There are people in my state running around with double-digit DWI conviction records.
Personally I believe you should lose your license after the first DWI, and you can't get it back for at least a year, and not before going through mandatory alcohol treatment and having a psychological evaluation that says you're unlikely to do it again.
2nd conviction? License revoked for life. Drive drunk after that without a license? Off to jail for a very long time with you. We can make room in the prison by letting out all the poor schmucks who are in for buying dope or patronizing prostitutes.