I don't know the exact situation in the Netherlands, but if it's anything like in Belgium the employer pays taxes on top of the employee's gross income. The total cost to the employer is therefore significantly higher than what the employee gets, even gross.
Employers pay taxes, but this calculator puts it as roughly 14k€ of costs for a 100k€ gross salary for the employee (Compared to 44k€ of costs in Belgium, which is why I left)
