Answer is easy : because it's only a project and you'll find it in many years not at all soon.
There are so many problem with this system that I don't even think this is possible with the way we plan a city street.
A car that want to turn might be crush by this tram over road vehicule.
It might work for a new city, maybe an american one. But no way you can put something like this in an old european city.
You also could have think of the non-stoping train system. It is planned for high speed train, but I guess it would be usefull for metro too.
What is it ? a the station, you have a part with some seats. People get on the seats and wait the next train to come.
The train arrive, release the part it took at the previous station with the passenger that want to exit at the stop and load the new one without stopping.