On the same € 65.000 gross, a worker takes home roughly 22 328 Kč more per year in Czech Republic than in Netherlands. That gap reflects the tax structure alone — before rent, healthcare, or savings behaviour come into play.
Housing is the first multiplier. Czech Republic has moderate rent pressure, while Netherlands has very high rent pressure. That keeps Czech Republic's nominal advantage closer to a real-world advantage.
Healthcare and pensions go in the opposite direction. Czech Republic runs a public healthcare model — Statutory health insurance covers essentially all care. Netherlands uses a public model — Mandatory private health insurance (~€140/month) with regulated coverage. The country with lower take-home often shifts costs that the other country leaves to your private budget.
Net-of-everything, a relocation decision should weigh strong public welfare in Czech Republic against comprehensive welfare state in Netherlands, plus differences in pension capture, social safety nets, and city-level cost of living.