Same doubt I had. My father lent some money so I could buy my house, but I paid back, and I had lent money to my sister some years ago, so it is more like a "family cash flow management".
When you're poor, and your family's poor, a lot of options are closed off to you. I know some people who were given old cars by parents; I always had to buy my own. That's just a couple thousand dollars for a used car, but that stuff adds up when it's not just a car, not just a loan for a house, but everything taken together.
In my country it is quite common that parents first pay for a wedding and then help as much as they can with buying/building a house for newly married couple. It is considered parent's duty to help their children kick-start their own family.
And because that usually means that parents won't save enough money for their own retirement then the children are supposed to take care of them when they do retire. Most of the time that helps maintain strong family bonds, but sometimes it does exactly the opposite.
That said I agree with the overall point that the term is so vague/broad it's basically meaningless if not clearly defined. Does living at home after college count?