Rant. My sister has 3 kids and refuses to have any helper so my elderly parents have to keep helping

My parents are v accommodating to my older sister so they don’t say no to her and I feel like she’s taking advantage of that. She and her husband can definitely afford a helper but she’s v particular so she refuses to have 1. My parents have to even drive to their place about 30 min drive each time they go and help out! For a few years now. Any advice? Tried to talk to her about it but she brushes me off… maybe cos she’s many years older than me. & she’s extremely stubborn. Don’t think she cares… Now I think my parents won’t help out for my baby :(