Parents shouldn't expect older siblings to help take care of the younger ones

I know it's very convenient to be able to have them watch or take care of the younger kids while you're not home but childcare shouldn't be their responsibility. If you need a babysitter, hire one. If the older kid wants to and is willing to help, that's great but don't make that an expectation. Your older kid isn't the one that decided to have more kids. Yeah, they live in your house and should contribute in some way but doing chores isn't the same thing as offloading your parental responsibilities onto them. The older kid should be able to have a life outside of home without hearing "you have to take your little brother/sister with you" or "you can't go because someone has to watch them". If you insist on pushing these responsibilities onto them, at least compensate the older kid somehow. "Hey, if you watch your brother/sister, I'll get you that thing you've been wanting or give you some cash."