[PhilWright]

I am all in favour of imaging a utopian future but basic economics do not suddenly disappear in the future.

Even if we ignore the ridiculous cost of $5 for the travel itself, what about the cost of travelling to and from airports? Uber, trams, trains, car and hyperloop all will cost money.

Are we going to have an airport in every suburb? I thought not, so that adds quite some travel time. If not using your own car then you have to wait for the Uber, tram, train, hyperloop to arrive as well.

I guess the plane will carry no baggage so that travellers can get straight on and off without any delays. Just hand luggage everyone!

[nicoslepicos]

One strategy for imagining possible designs is to think in extremes in order to stimulate the imagination. I'm not suggesting this type of trip would be feasible for $5 in the next decade, maybe not the next 50 years, maybe not the next 150 years, maybe it'll never be possible - but as a thought exercise it's interesting to consider what would need to happen to reduce the cost & friction to that point.

Let's consider what some of the things that would need to happen are to address the problems you bring up:

Cheap, virtually free sources of energy would need to play a part. To solve the issues of airports, maybe it's that we have personal flying crafts capable of vertical takeoff instead of relying on centralized airports. Maybe there's a way to get picked up by an airplane at your house (not saying I have any idea what that might look like, but it gets you to start imagining approaches around the constraints). What would possible solutions to the baggage issue you brought up be?

This thought exercise prompts is meant to prompt ideas around what things could look like in the extreme, so that we can then consider what might need to happen to get to something like that. For sure there's lots of hurdles, and some of them may actually be fundamental limits - though I'm not sure that such limits exist here.

Last point I'll make is that economic assumptions do change over time substantially. Until the industrial revolution in the 18th century, economics looked very different than it does today - GDP per capita did not increase as any increase in GDP was met by a proportional increase in population (https://en.wikipedia.org/wiki/Malthusian_trap). The assumptions we have about how our economy functions today could dramatically shift over time as technological advances shift the dynamics of the system. Abundant food, energy & energy storage, along with automated skilled robotic labor, could challenge many of our current economic ideas.