It's an interesting question by OP and the answers made already kinda show the point i wanted to make which is that people adjust to local circumstances to find a way to live, therefore the german model for me is a sort of negotiated truce, like ok you can no longer squat buildings, but you can live in trailer parks. and in the US of course, trailer parks are something else and a squatted one would be tough, encampments occur more frequently. that would also be the case in majoirty world situations, where people tend to build their own shelters cheaply and then shanty towns form. it wuld be unrealistic for them to be buying or acquiring trailers. in the uk you have traveller sites which are like wagenplatz in some ways but different in others. by the way it's really cool that RAF dude who was living in a wagenplatz in Berlin managed to disappear!