Honestly - and I hope this didn’t happen to you - it takes a surprising level of indifference for kids to pick up a “this is wrong” signal.
I’m not going to speak for anyone else, but if I forget a thing and “fixing” it is as simple as saying sorry and doing it the next day, I’ll do it. And I will keep doing it on a loop if need be _because I care_.
And that’s often the easy sign for this stuff. Did your parents forget and _not even try_ to show that they care?
It’s the sheer indifferent callousness that stands out starkest to me. It doesn’t take much, I’ve found, for people to state outright “you’re wrong to expect me to care about you.”