I find this very interesting from the tax perspective too.
In case you reduce your pay by 20% to accommodate for fewer hours, in many countries with progressive tax rates, the effect on take-home pay in absolute terms is not as significant as relative.
For example, in Germany, 100K gross leaves you with 57 after tax. Whereas 80K results in ~47k. In absolute terms, it is 'just 10k less', on a salary of 57k, but with 20% less working hours.
In case you reduce your pay by 20% to accommodate for fewer hours, in many countries with progressive tax rates, the effect on take-home pay in absolute terms is not as significant as relative.
For example, in Germany, 100K gross leaves you with 57 after tax. Whereas 80K results in ~47k. In absolute terms, it is 'just 10k less', on a salary of 57k, but with 20% less working hours.