Because 40k€ a year is not a lot of money after the high taxes. For example, for a non-married 25 year old 40k€ p.a. results in about ~2k€ net per month after t

Because 40k€ a year is not a lot of money after the high taxes. For example, for a non-married 25 year old 40k€ p.a. results in about ~2k€ net per month after taxes. When you further deduct the costs of a apartment rent, utility bills, car, food, insurances, phone bills, various little "fees" that are actually taxes (e.g. Rundfunkbeitrag), you are very lucky if you have 1k€ left left. That is not a lot of money to send home.