J.S.
I always based these things on my trust in my kids, my feelings on their maturity. See my kids knew right from wrong and they had no trouble voicing that. They always told me what was going on and I never had any reason to think they were anywhere else.
My daughter's school was 15 miles from home, the fields where she practiced soccer another 45. Considering I completely trusted her judgement why on earth would I make her come home, scarf down dinner and run back out to a friends house? Oh some of her friends lived 15 miles past the school between the fields and the school. That would be an extra hour of driving just to placate me.
The other thing is why I could trust my kids was they valued that trust. They could see I trusted them more than their friends were trusted by their parents. That made them feel more mature, more responsible and they wouldn't do a thing they thought would violate that trust. I in turn did nothing that showed I was questioning their responsibility unless I had a reason. Seems to me, drive an hour out of your way so I can see you are alive, a clear indication I didn't trust them to still be alive.
The two oldest are adults now and believe it or not they did nothing wrong. They told me a few stories from college but not high school. I didn't worry and apparently I had no reason to worry.
My kids did call every time their plans changed.
Oh yeah and they also worked all summer. Just too much going on for them to be calling mommy every hour. Either you trust them or you don't. If you don't trust your kid to be making good decisions you shouldn't allow them to drive on their own. Based on my teen years you could get into plenty of trouble long before dinner time.
Per your what happened, I figured you trusted your child, that is why I pointed out the value of the trust. Kids that are micromanaged are the ones that given an ounce of freedom do really stupid things. Kids you have grown to trust value that trust, it is worth more than some stupid adventure.
Seemed like during the summer breakfast became the family meal.