OP, with the greatest respect, you don't have children, which became quite clear in the way you have written your post.
I treat all of my children with respect, and have always asked them to do things with a please / would you mind / thank you etc. Children can become quite stubborn, and I have, at times, had to be more direct with them, similar to the manner which you totally disagree with - usually if they haven't listened after being asked a couple of times. I certainly would not say "get in the car now" in the first instance - that is just plain rude.
However, you spending time with a friends child, and bribing them to do something with chocolate, is nothing to be proud of - in fact it will make the child more stubborn if they know a treat will be the end result of such behaviour!
Let's be honest, we all have to do things we don't want to do throughout our lives, whether you are a child or an adult. It's part of life. 🤷♀️
I suggest you have a couple of children, be a mum 24/7, 365 days a year - and come back in a few years time and tell us all how you are getting on........