Trams, Trolleys and Streetcars

I've considered that - but I think that would be way to complex and unpractical. Imagine that you are a tourist and you are asked to chose a correct "tram" in a limited time and while the tram is moving (walking isn't easy + you have to drag your luggage along ). Or imagine that each half of the passengers of each "independent module" decide to change the tram utilizing that one single door - having to walk along the tram, avoid all the other passengers... Or imagine somebody is trying to change the tram with a child carriage. Or imagine someone trying to change the tram in a wheelchair or with a walking aid. And since this is being done on the move, the driver can't just wait another 30 seconds until most are seated - because the trams would be already disconnected again by then...

Using only two doors for onboarding / offboarding of 140 people is a bit on the edge anyway. Here in Prague current Skoda 52T uses 5 sets of (visually) much wider doors to on/off cca 240 passengers, previous Skoda 13T used 4.5 doors (one door had only single wing) to on/off cca 280 passangers - and that was already too few doors and had to be re-designed (whole inside had to be re-done, capacity was reduced). The standard Tatra T3 - the one from profile picture of this sub - had 3 doors per 110 passengers - ( but admit-ably there were stairs).

It should be noted that it is unlikely that any "practicality constrains" were given to the participants of the design competition. They just wanted something futuristic - and IMO succeeded.