1. Put your foot on the brake before starting your car.
2. Always leave your car in gear when you turn it off unless you're using the starter.
3. If you're going to leave your car in gear, use reverse, not first. It's a stronger gear.
4. Before you start your car, always put it in neutral.
If the shop had put the handbrake up and it was some woman that never uses the handbrake and she drove all the way home with it on, they'd have other problems so that's probably why they don't do it. The fact you do it differently is not their problem.