My son threw a conniption fit in public. Leaving the zoo, heading back to the car. I had him under one arm (kicking & screaming) and my "dad bag" under the other.
A thoughtful neighbor yelled down at me "Stop beating your kid! I've called the police!" Okay then. I put my kid the car (leaving door open), sat on the curb, and waited for the cop.
Last thing I want is an AMBER alert and then get pulled over. Then I'd be late for the parent handoff, and then the fur really flies.
Older (experienced) cop shows up. My son's still grumpy. Cop sizes up situation and sends us on our way. The 15 minutes served as a pretty good cool down.
In general, abused kids do not throw tantrums in public, normal parents keep their cool when their kids just need a nap.