Because some countries have much, much worse tenants rights.
I moved from Ireland to Germany and in Ireland:
* There is basically no protection for rent increases, some people are being told their rent is increasing by 50%
* Can't change your apartment. Not allowed to paint the walls, nearly all come with furniture, better make sure you don't damage any of it.
* Oh the landlord/landlord's relative wants to live in the apartment. Eviction time for you.
* You give your landlord your deposit. Let's hope they can find it again if you move out.
* By default, no pets allowed. And many landlords will say no.
* Did I mention about the rent increases?