You are very misinformed GPS. First of all, the article specifically says "deputies set up a road block, and checked each car coming into or out of the street in question for drugs." That is not a casual conversation. That is a search for dugs. Says it right in the article.

Secondly, the OWI stops that have been ruled Constitutional are supposed to be very limited. They are considered searches by the court, not casual encounters as you describe them. However, because of the public safety benefit, the court decided that the benefit outweighed 4th Amendment violation. When an OWI stop does occur, the police are supposed to only check for intoxication, and nothing else. Although many other states use this as an excuse to also check for people driving with an invalid license, or out of date tags. However, the legality of that is actually in question. Different courts have ruled differently in that regard.

Either way... I believe that OWI checkpoints are also unconstitutional, and should be abolished. Many studies have also shown that states which use OWI checkpoints have actually seen an increase in the number of drunk driving fatalities as well.

The police don't have legal authority to simply take anyone off the street and frisk them for anything simply because they feel like it. That's not the country we live in.