I looked it up and it can indeed go up to 13.5% inclination but they can only run powered cars, no attached wagons. That reduces capacity.

I don't want to shit on trams. I don't like this bus vs tram bashing in either direction. I'll happily take either improvement over a sea of cars...

Don't they use rubber tired trams, aka guided buses?

I don't quite remember what they're called but in the UK there's both old mining trains and old cliff trains/trolleys that use toothed wheels and toothed tracks on the hill portions to go up/down hill with little issue, obviously it's only safe for some gradient, but still with the right gearing it would be of possible