TBH it looks like a remodeled attic room. And the way it's all crammed in a corner suggests that it isn't taking up an especially large amount of space. We don't see how large the rest of the room is.
I live in a pretty average US home (built in 1971, raised ranch similar to this:https://photos.zillowstatic.com/p_e/ISi3u8fp8ljszu1000000000...) and there's plenty of room in the 2 non-master bedrooms to dedicate half the room to a crammed-in arrangement like this, with a bed crammed in the other half.
I live in a pretty average US home (built in 1971, raised ranch similar to this:https://photos.zillowstatic.com/p_e/ISi3u8fp8ljszu1000000000...) and there's plenty of room in the 2 non-master bedrooms to dedicate half the room to a crammed-in arrangement like this, with a bed crammed in the other half.