The most likely cultural trait responsible for the difference in workweek length between the U.S. and the Netherlands in 2020 is:
**The U.S. culture prioritizes capitalism, while the Netherlands’ culture prioritizes health and welfare.**
This response highlights the emphasis on work and productivity in the U.S., driven by capitalist values, in contrast to the Netherlands, where there is a strong focus on work-life balance and social welfare, resulting in shorter work hours.