Never could understand this, and yes it is murder.
A few years ago, while going into a CostCo, I spotted a young child in a car on a very hot Southern California day - the child was crying and whimpering. Doors were locked, windows rolled up, no one in sight.
Tried repeatedly to call 911 and could not connect. Told husband to run to his truck for a heavy wrench, I was going to smash out the windows. I was trying to talk to the child who was hysterical - as I was becoming b/c I couldn’t get through to 911 - someone got the manager of the CostCo who contacted the police. Husband came running with the wrench when the mother (or babysitter) apparently saw us at the car, got in and screeched out.
Police came into the CostCo - I didn’t get the license plate number or make of the car b/c I was so focused on the poor baby in the car. Would have taken a photo except I was frantically trying to call 911.
I witnessed this once as well. Going with my daughter to the vet to pick up a neighbors cat (runaway repeat offender), we stopped off at a fast food joint to get some breakfast. I saw the baby in the carseat, inside the car, with the motor running and the windows sealed.
I called 911 and looked for a tire iron. Fortunately the cops came so I didn’t have to punch out any glass. They looked in the FF joint for the parent - no joy. It turned out that she had gone into a grocery store. I waited around long enough to watch her being cited.