[def_true_false]

Why can't you have trams travelling at 80km/h? That's around the max speed of some of the trams used in Europe.

[Tade0]

Because at that speed its braking distance is close to 200 metres, so you need to separate such a vehicle from the rest of the traffic.

There exist implementations of this, but it's essentially a train with extra steps.

[bombcar]

Because pedestrians and drivers are idiots (or if you want to be nice, have lapses in judgement).

Whereas it is possible to have a subway where it’s completely impossible to get on the tracks without heavy equipment or the right keys.