Your parents are doing parenting for the first time too. Everyone’s a beginner at something.

Nobody arrives at raising a person with any experience of raising that person. The adults in your house are improvising against their own upbringing, their own worries and whatever advice reached them, and doing it while tired. That does not make every decision right. It does explain why the decisions are uneven.

Next time a rule seems arbitrary, ask where it came from instead of arguing against it. You will often get a story, and that conversation goes somewhere quite different from the argument.