Not really as far as I know. Providers in Germany have more or less standardized on Fritz!Box from AVM and the router comes with the admin password available. Updates are then fetched from upstream AVM.
But the key point here is device independence - by law, providers need to give you all information required to establish a connection to them. This allows you to run a Linux or BSD box as a router should you wish to. It somehow makes up for the slow broadband speeds you can get.
Are there Linux or BSD boxes with ADSL or DOCSIS physical layers present? I use a separate modem and router, as do most people in the US that are not renting equipment from their ISP.
But the key point here is device independence - by law, providers need to give you all information required to establish a connection to them. This allows you to run a Linux or BSD box as a router should you wish to. It somehow makes up for the slow broadband speeds you can get.
*Edit: complaints about slow broadband speeds