It may seem simple, but when your child says "please" and "thank you" when you fulfil one of the 10,000 requests they throw at you every day, they're acknowledging that they're asking you for a favour and you're completing that favour, versus treating you like their own personal servant. It's an important habit to start at a young age, even when you're doing things for them they couldn't do for themselves. Remind them that restaurant servers, childcare providers, grandparents, and anyone else who helps them also deserve the kindness of a "please" and "thank you."