Nup. My MIL watches kids every 2nd saturday so i can work, and for appointments for other kids ie toddler terror and lots of open stairs don't mix. She is happy to do so to help us out and for me to get work...11 years as SAHM doesn't look good on resume ( which sh*ts me but that is the truth) she also watches kids when i do volunteer work.
I have no neices or nephews, but i do watch neighbours kids ( differrent lots) sometimes for whole day and think nothing of it. What goes around comes around they repay by doing same.
My BIL and SIL with no kids take my kids for week on holidays up north.
But honestly if the relative had no kids and it was 2 full days maybe some payment.
I might add i feel guilty as hell that MIL has to watch kids every 2nd week( hubby works every 2nd saturday). I think if I paid her i would not feel guilt. But she will never take it, she tells me off when i buy her flowers as " Why I don't deserve those" ( note she never ever gets flowers from anyone so i love to give them to her....she told me 14 years ago that she got flowers once).