How homelessness is measured varies massively between countries. So Britain has an estimated 4751 people sleeping rough, but 307,000 people who are homeless, i.e. living in temporary accomodation, sofa surfing etc. The USA has an estimated 190,000 people sleeping rough (in cars, tents, on the streets) but only counts a total of 540,000 people as homeless. I don't know how the American figures are counted but the German ones are probably estimated in a similar way to the British ones because we live standardised statistics in the EU.