Voice of Reason, good points. I am reminded of a time when our now college-age son was in high school. Fortunately, our home was the hang out for his group of friends. We encouraged this and were glad that we knew his friends and saw them come and go from the house. We live in Johnson County so it is not like the small town I grew up in where my parents knew everyone in the school. Anyway, his friends often asked our son why we (the parents) never went out of town with the point being that they could not have an unsupervised party at our home. We answered that we had already done our "traveling" before we had kids and now we were focused on being parents. In the 4 years of having a large group nearly every weekend, we had 2 instances of alcohol in the house. These were easy to catch because we do not drink and could smell it 3 rooms away. In one case, the drinker was of legal age, but was escorted out of our home because he had no business hanging out with teens and in the other case; I drove him home to his parents. After this, my sons told me their friends were too afraid to come to our house with alcohol. This is a good thing.
One rule of our house is that you always come in and tell the parents you are home, regardless of the time. My parents had this rule with me over forty years ago and it just seemed natural to follow when I had teens. My younger son asked why we had this rule and then commented that it was a good one because we would always know if they had been smoking or drinking by the smell.
I am not saying we have not made mistakes, but we try to avoid those we can anticipate. We have very few rules: wear your seatbelt, don't drink, smoke or do drugs; basic safety concerns. We try not to sweat the other lesser rebellious ways of teens.