> In economics, a normal good is a type of a good which experiences an increase in demand due to an increase in income, unlike inferior goods, for which the opposite is observed. When there is an increase in a person's income, for example due to a wage rise, a good for which the demand rises due to the wage increase, is referred as a normal good. Conversely, the demand for normal goods declines when the income decreases, for example due to a wage decrease or layoffs.
It's entirely expected that people will want to consume more comfort and safety at their income increases.
If you compare different countries, you will find that these kinds of things track with income much more than with history of union activism.
For a striking example see https://pseudoerasmus.com/2017/10/02/ijd/ which is an article on the divergence between Japan and India. Japan has a long history of labour repression, especially compared to India. But by and large Japanese workers have a it a lot better today than workers in India, especially if you go by what's happening in reality and not just by what's promised on paper.
And that difference tracks with the difference in incomes between the two countries, but stands in stark contrast to what we would expect from your sketched theory of union activism driving these things.
It took decades from the demand was there until it became normalised to offer it, with concession after concession won as direct and explicit outcomes of industrial action.
That good conditions are offered far more easily when a working population is in a financial position to walk if it's not offered is entirely unsurprising and irrelevant. That you can't possibly win the same level of outcomes when the financial position of employers doesn't allow it is also entirely unsurprising and irrelevant.
Nobody expects magic. Nor does anyone suggest that there aren't other factors also at play.
History of union activism is an explanatory variable that doesn't add much to the mix, and if anything is rather contradictory and noisy in the end.
Someone with more income might exchange more money for time/comfort, if all things are held equal including the price.
I think the inverse is true when you consider exchanging things other than money for more comforts.
That is to say, people will pay more money because they have more of it the higher their income (because the marginal value of each dollar goes down)
Asking would you be willing to risk your life for more comfort, that answer changes. The higher your income/comfort/happiness, the less willing you are to risk your life for more comfort.
The less people have to work, the less they are willing to risk their lives for more free time.
Who would risk death protesting for more leisure: someone working 80, 40, 20, or 2 hours?
And indeed both the level of union membership and the militancy of union actions supports that. Union membership cratered in developed countries and conditions have improved, and labour conflicts have gone from being outright armed in some cases in the past to being mostly relatively tame and regulated affairs.
