A cricket match keeps a car parked for most of a day, and it only takes sidelights or an interior lamp left on to empty an older battery in that time. After the final over the car parks drain slowly, so a dead car at the stadium is best handled calmly: message us with the car park and the nearest gate, and stay with the car.
Training evenings cause a quieter version of the same thing. Parents wait in the car outside the academies with the engine off and the blower, screen and phone charger running. An hour of that, a few times a week, leaves the battery low enough that a hot day finishes the job. Keeping the engine running while you wait avoids it.