Lowering the cost of travel to 0 would mean implementing a technology by which anyone can simply desire to be somewhere else, and they will instantly teleport to that new location.
returnInfinity is simply lying about not doing double (or more!) the amount of travel in that case.
I’m sure that he/she would ride a lot more if it cost nothing, but I think the point is valid: even if Uber could 10x or 100x productivity, they could not do the same with income, because there is a limit to how much people actually need to go places.
That’s true but fully autonomous driving alone might double my car travel. Going into the nearest major city is a pain. So is driving into the mountains. Operating costs and time are still costs. But not having to drive would really change the game for me.
Who said anything about instantly teleporting? Uber could cut the cost in money to 0 but still operate cars which are bound by the laws of physics and the rules of the road.
Maybe returnInfinity already spends 12 hours a day in Ubers, or otherwise has them satisfy all his transportation needs, and couldn't usefully double his usage of them.
It's impossible for them to cut the cost to 0 (without using magic), but that doesn't make it impossible for us to talk about what the cost being 0 would involve. Travel time is one of the costs you pay for Uber's service. That you don't pay it to Uber doesn't matter. If Uber reduced that cost to 0, you would use Uber a lot more.
returnInfinity is simply lying about not doing double (or more!) the amount of travel in that case.