I haven't bought any of the DLC yet but I think a huge missed opportunity for the game was to add a ferry system. It's clear some maps have Islands that are too spread apart for bridges to be built and Tropicans are forced to use little boats to get around. They're very slow, tedious and look quite ugly too.

Having a Ferry transport 50 - 75 Tropicans at once would be such a game changer and could adjoin buses. While the Metro is basically teleportation it only gets you so far as Tropicans will still try to use the shortest route a lot of the time or if they're teamsters