Telling someone to "be a better person" (by "telling" I really mean passive-aggressively demanding via social media or shaming them into) is like telling a 12 year old girl with poor posture to "sit up straight".
If she doesn't roll her eyes and completely reject your request she MIGHT display proper alignment but only for about 60 seconds while you're watching. Then her muscles will fatigue and she'll go back to her comfortable hunched position. You'll tell her again, "sit up straight" and the result will be the same. After 5 years of "bringing awareness" to her undesired spinal position no progress will have been made and you'll be left confused and even more angry than you started.
Chronic shitty posture is due to years of hunching, muscle atrophy, neurological damage and tension. It takes years of hard, dedicated, and sometimes frustrating work to reverse the damage and to adjust bad posture even SLIGHTLY.
Substitute bad posture for "bad behavior" and the case is the same; assuming the person in question is #1 AWARE of said behavior and #2 WANTS to be different. So now that you've posted it to Facebook, copied it to Twitter, bought the bumper sticker and tattooed it on your forehead what do you plan to do to affect real change? It's called a "movement" for a reason. Maybe it's time to move.