> The trams also switch to the left side as the doors are only one side.

... Wait, what? That seems like a serious false economy...

Buses also have the doors only on one side usually, if you're just running trams on the surface in traffic you'll probably only need them on the pavement side of the vehicle. It's just got weird in this case the assumption the choice was made on changed after they already had a fleet.

A set of crossovers has a high upfront cost, but compare to the added seating capacity on every tram car every day for decades and it doesn't seem so bad.

You might think you could just have trams with doors on both sides, but the geometry isn't expandable, so you're really just trading capacity. The station needs to be built anyway, so the costs of building the tracks differently isn't that high.

Same in Gothenburg. There's a single underground station, with the platform in the middle, so the trams need to cross over. Another underground station is planned, but it will have the tracks in the middle instead.