Because of internal immigration. Due to povery, lack of investments and lack of opportunities, the countryside there is becoming empty fast as everyone moves from the villages/small cities to the 3-5 big metro areas in the country with top universities and cushy skilled desk-jobs instead of bumming around in rural areas begging for low paying manual labor type jobs.

In western europe, rural areas and small towns, although boring AF, usually have some trade schools or small collages and local industries of their own that still keep locals there and sometimes attract foreigners so not everyone has to scram to the big cities, although big cities there have major housing issues too.

From what I hear, salaries in some eastern european countries, like Romania, are higher than western europe, in local purchasing power.

Wages there are high for skilled workers who can sell their work on the global market, like tech workers, but people are tired of the herd stupidity of the population, political corruption, the incompetente of government institutions, underfunded healthcare, useless police, etc. so they pack up and leave even though they'll take a hit on lifestyle frivolities.