I'm afraid that your understanding is incorrect, Hymie.
The water companies are responsible for the pipe to the boundary of the householder's LAND - though for some people this may also be the boundary to the property (if the property abuts the public highway).
I read your link - and believe that Thames Water do this free repair as a gesture - they are not legally obliged.
The question asked is it fair? - too right it is. You'll be wanting us taxpayers to pay for your leaking taps next. Your property, your problem I'm afraid to say.