Because it is! Looking online it looks like prices in this area are around €250k for a 400-600 sqft apartment. It looks like land just outside of this area goes for ~€200k for 0.2 acres, houses go for around €500k - 1.5mil, and townhomes go for around €200k. Rents in the area are fairly affordable at ~€475 per month (one bedroom city center) but the average salary is only ~€950 per month. Also the population is only ~15k.

The person who made the post in the image is comparing apples to oranges. My small-ish US town has a population of 10k and you can get 3 acres of land and a 2000 sq ft house for $250k. Gas station and grocery store are 10 min down the road by car. The average monthly wage is $3400 in this town.

Basically, the average person in the pictured town would need 22 years of their full salary to pay for a townhome while the average person in my town only needs 6 years of their full salary. The American mind may not be able to comprehend this picture, but it's not like most Croatians can live there either.