I was the kid who was charged like that, a third of my take home. It was presented as a non negotiable, i paid it, it taught me some lessons about managing money.
I left home, unrelated reasons about a year later.
Younger sibling, got my old room as a sitting room, with doorway knocked through to her bedroom. My stuff was given away. She was never charged anything.
For me, it was part of a transactional relationship with my family, and in the end, i had nothing to do with them. Mum died about 5 years ago, i went to funeral. Dad is alive, somewhere. Sister reaches out occassionally, to remind me i have two nieces, but as i keep telling her, my upbringing was different to hers and i really don’t consider myself to have close family, i wish her and her family well, but i don’t consider them family.
I don’t want any of the inheritance, thankfully i became financially wealthy myself and taking few hundred k at some point feels wrong because i really don’t consider them family.
Not the same situation i hope, but the money lesson i was taught, wasn’t about budgeting, managing it, investing it, it was just transactional.
Hope you are better parents than i had.
On a different note, we have one kid at private school and the older one didn’t get that as an option…. We will even out the 130k when the older one needs it for a deposit. That was the lesson i truly learnt, be even.