"Every parent should care for their child without the expectation of something in return."

That is exactly how I feel. My children owe me nothing. I expect only the reward of being able to love them and guide them as they grow up, accompanied by the bittersweet paradox of knowing they must embark upon their own life journeys some day. They won't be around forever and neither will I (in a different sense). I don't expect my kids to be my carer or my provider and I wouldn't ask it of them. But I can see how in the past, as you say, things were different and it would've worked differently.