DSs were biking and scooting along the foot path from one end of the park/playground towards the carpark. It's 4.45. There are only a few people left.

I notice a car drive off with the stroller still parked next to the door. Angle parking, and stoller is on the non-driver side. She/he obviously didn't look back. It's a very big park/playground, on a busy 4 lane route. Not the best suburb, and plenty of foot traffic too. Fairly cheapish (i think?) looking stroller.

What would you do?