Its hard to frame a question across languages and cultures.
The ladder metaphor isn't the worst.
The ladder metaphor isn't the worst.
Like, if there is no consensus on what the scale means the answers will be too culturaly dependend and random between individuals.
In my experience doing surveys "was the food good?" after say a conference is way easiee to interpret than some scale answers.
If the society/culture you are living within. Is well off, but swamped with cravings that it could be better. Then you are less happy.
This study isn't trying to measure how 'materially well off you are', it is happiness. So if you are un-satisfied even with your big house, and un-happy, that still says something.