But they only rent the last mile from the Telekom. Starting at the DSLAM they usually bring their own infrastructure. (Except reseller contracts).

In the last years there also have been many small, local ISPs popping up, often partly owned by the city (Stadtwerke). Some start rolling FTTH connections and finally bring germany to the internet-first-world.

Cable providers, at least Kabel Deutschland (which is the only option here where I live), are sadly no alternative, while they offer high bandwidths without volume based throttling, the traffic shaping they do at peak times and for torrent traffic is ridiculous and makes their service almost unusable.