Cate's actions would not be looked upon favorably in my family. At close family gatherings, ( which is what it sounds like the OP is describing) everyone pitches in. This does not apply in other hosting situations.
My DH's sis sounds similar to Cate. She never offers to help out at her parents, our house or her other brother's house. And she never hosts. When most family events were at her mom 's i didnt say anything even when i was in the kitchen with my DH washing dishes. But now most events are at our house. So we now assign her jobs. Even my kids do it because they realized how unfair it was that she never did anything.
"Lisa, you rinse the dishes and I'll load."
"Lisa, please fill the glasses with ice."
"Lisa, would you help me clear the table."
In my SILs case, she was never required by her parents to do any chores. Her 2 older brothers were, but I think because there was a large age gap, they were the ones doing the work while the "baby" sat. And after they went off to college, it never changed. Plus the "our little princess" syndrome was well at work in that family. At 40, she is finally getting over that.