I think that actually applies to all the lines, massive stretches of the becknham line are old railway tracks and a few of the new addington stretches are as well.
Sheffield's trams are very different. Apart from the Meadowhall line and the outer bits of the south eastern route vast chunks of Sheffield's trams run on the roads. It's a very different system to Manchester and Croydon. Our road network is also different too. It is well known that it causes problems for some cyclists because it pinches key routes in certain bits of the city.
You tend not to hear too much moaning about it from cyclists as a lot of the city's cyclists live in an affluent bit of the city away from a tram routes and therefore encounter tram tracks slightly less often than they might otherwise.