Property laws and their enforcement are vastly different in the US, which is the primary reason there's a cultural difference. In most European locations, squatters can hijack or otherwise gain access to water and electricity; in the US, that's almost impossible due to regulatory control and remote shut-offs. European squats I've visited are habitable, while the ones I've visited in the US are not. Most squats in the US suffer from poor hygiene, lack of running water, and cooking usually takes place on open flames. European squatting is like a poor but functional commune; US squats are like camping in a city.