As someone also living in the Midwest, what's your issue with it? A bunch of people are doing a thing. They see a kid. They stop doing it while the kid is in sight, so they're spared seeing it.

What could possibly be the issue? If anything, it demonstrates Midwestern values pretty well: Freedom, and a moral, not legal, code that people voluntarily follow to prevent kids from being exposed to potentially-harmful things, without any government needed to enforce it!

If anything, it's more considerate than where I live, where people will openly smoke in front of children, which is arguably more harmful, because smoking has second-hand effects, unlike intravenous drug usage.