Brisbane's 3 Public Transport methods

So in sunny Brisbane we have three different mediums (is that the word?) which are integrated into our public transport system. Bus, Rail, and Citycat (there are ferries, which are a poor mans citycat ).

So they all have their uses, but one interesting thing I find is how their ticketing acquisition structure differentiates.

Bus - buy ticket from driver WHEN you get on
Train - buy ticket from vendor/machine BEFORE you get on
Citycat - buy ticket from vendor/mahine AFTER you get on

Which is better? Let's discuss buses vs trains for a bit, as this is what I have most exposure to.

You are running late for a train, you see it pulling into the station as you run to catch it. But you don't have a ticket. Do you jump on train without a ticket and risk a fine, or buy a ticket but accept you will miss that train, possibly waiting half an hour for another? But you run to a bus stop just as the bus is arriving! hurruh you made it. you jump on and get a chance to fish some cash out and buy a ticket.

So now we are on our form of transport we carry on. However the pro/con is now reversed. At each train stop, there is a specific stop time, usually under a minute where people can get on/off the train, and we continue on. All very uniform, no delays.

As each bus stops, you get everyone fishing their cash out, trying to find change, ask the driver what ticket they need, and you can end up with lengthy unpredictable delays at each stop.

Now look at the city cat. With the city cat, there is only a small delay at each port allowing people on and off the citycat, no requirement to have a ticket for this part. One on the cat (and after it has perhaps taken off and you are en route along with all other passengers), you can purchase your ticket.

Citycat is obviously superior! Why can't we use this on other forms of transport?

When visiting Melbourne, the Tram system there is run like the Citycat. The driver is seperate and only responsible for driving the tram, each tram has a ticket machine on board so you can buy a ticket. Would be great to have something similar on trains, though with the overcrowding we have I guess that's almost impossible to use in rush hour.

An interesting thing we saw in Japan with buses was that you pay for your ticket when you get OFF the bus. Gives a bit more leeway, as once on the bus you can sit down and work out how much you should pay. Gives people a chance to organize themselves more than when they get on (when running late for a train, you can't stop and pull out your cash in preparation easily)