If they wanted to do that they'd need to have global streaming rights, which would cost much much much much more than the marginal bandwidth taken up by the fraction of users with the tech savvy to set up a proxy.
The Olympics are bought collective for Europe by the EBU/Eurovision and then their members broadcast them so for the Olypics the BBC may have Euopean rights from the IOC.
Also, see http://www.broadbandtvnews.com/2011/01/27/kpn-tv-get-domesti.... The reason that the Netherlands has BBC television probably is historic (and fairly weird; even in the west of the country, one needed precisely the right kind of atmosphere to receive a fairly noisy signal), but nowadays, money does change hands.