well you are right, single player needs trains, buses, subways and airports/seaports. I would be willing to pay for A REAL CITY BUILDER that had these features, and i would also pay for extras beyond that.
However you are missing something IMPORTANT that you will see upon release and i would tell you but am unable to at this time.
Please do yourself a favor and DON'T preorder this game and wait till you read some reviews before spending $$$.
In the meantime think about possible reasons why the demo is so short.......