Where have you heard that before? In these inflationary times every little bit helps in keeping costs under control. Let the young ones know it's a trade off, managing your finances is about the choices we make.
They can help by understanding that the family can save money on electricity when they turn off the lights in the room when they leave that room. Besides they can play video games in the dark anyway because the screen is backlit. So don't even turn on the lights to begin with. Maybe that's a bit harsh but give it a try. Let them know we all share the costs of the household and they have a part to play. My message to young families for the kids is tell them "If you're not generating revenue then you can help by reducing expenses, or get a job.... and I love you. :-) 1
Footnote
1
The USDA estimates that parents can expect to pay between $15,438 and $17,375 a year raising a child in 2022, which can vary based on region and household income level.