This tram goes up a steep hill. On the ground you can see a third line of "tracks". Those a for a gear the tram uses to pull itself up the hill. It's the only one in Stuttgart that has that. Because that hill is so steep, they allow bikers to take their bike with them and because many use that offer, they added the extra bike carriage.

You can easily empty 100Wh of an E-Bike battery going up that hill. It is indeed very steep

Too many dangerous, busy main roads with no bike lanes and no space for cyclists. It goes the cyclists the ability to ride distances, avoiding the impassible roads, to get to where they can ride.

That's like saying "why don't you just swim across" instead of using the car ferry.