Nobody has forgotten the trams, you can see it here: http://www.train-fever.com/2013/12/vehicles-overview-and-merry-christmas/ 🙂
Also in game electric tram will be available since 1881, and before this you can use horsecars.
About metro – as far I know, it can be added in future DLC, if the release will be successful.
About underground trams – like metro, not in release, as far I know.
Btw you reminded me about very interesting thing – cargo trams! It really was popular in first half of XX century. I not sure what they will be in release, but hope what it will be able to realise with modding. 🙂