Like cable, internet connection, or Costco membership - it's per household not per family.
2017 (https://archive.is/KFZtP) "No matter which plan you choose, you can install the Netflix app on as many devices as you want, and enjoy as many TV shows and movies as you want, anytime, anywhere." In 2017, not only were they not talking about households, they were explicitly bragging about how you can watch on any device in multiple locations, which conflicts with the concept of a household they are pushing now.
2021 (https://archive.is/OzbRU) "The plan you choose will determine the number of devices that you can watch Netflix on at the same time. With all of our plans, you can download the Netflix app on all your favorite devices and watch unlimited movies and TV shows."
But now in 2022 (https://help.netflix.com/en/node/24926) "As a Netflix member, you are charged monthly on the date you signed up. A Netflix account is for people who live together in a single household. Learn more about sharing Netflix."
No, it’s clearly supposed to be that one account covers multiple people. GP is fine to complain whether they have enough money for two houses at once.
What about kids who have divorced parents and stay at a different house on the weekend? Do they need to get two separate accounts because “their parents can afford two houses?”