I'm guessing you mostly mean light rail, since there's not a lot of money going into urban heavy rail. There are a couple of reasons why these can be better tha

I'm guessing you mostly mean light rail, since there's not a lot of money going into urban heavy rail. There are a couple of reasons why these can be better than buses: - You can invest around them. Because unlike a bus, a tram can't just be upped and moved somewhere else developers are able to build housing and services confident that there will be service. - They are easier to segregate and run at speed so that you can run limited stop services that are credible. I suspect this is what you are getting at with airports, but I'm not sure why you think an airport is the only reasonable use for fast limited-stop operation - They can carry more people easily. 2 or 3 car trams are the norm, and the smoother ride and increased safety means that it is much safer to carry lots of standing passengers - People like them. You can actually get people out of cars onto a tram, where faced with a bus they will assume that it is going to be dirty and they will be robbed (however untrue that is)