[spikels]

Actually it's mass public transit that can't scale. Despite $1.3T in cumulative subsides US public transit usage is tiny: ~1.5% of trips and ~1% of passenger-miles.

Getting 100 people in a bus is not "easy" because very rarely do 100 people all want to from/to the same place at the same time. We end up bunching people in both time and space and making multiple stops and/or connections - which all make the journey longer and less competitive with alternatives.

And even then buses are only near capacity in our very biggest cities (top 10-15) for a hundful of hours during weekday rush hours. For example, in SF while buses/railcars may occasionally get crowded they are usually empty: Muni averages only 6 passengers per vehicle, BART only 8 per traincar. On a passenger-mile basis this makes the service very expensive (Muni ~$4 and BART ~$2 including capital) and very energy inefficient (Muni(LRV) ~400Wh and BART ~600Wh). Explaining why both systems are struggling financially and require massive ongoing subsides keep operating.

Because busses/subways/trains (i.e. mass transit) require lots of passengers to make financial - or even environmental - sense they will always be a niche, if very important, part of transportation. Robotaxis are competing in the much, much larger car/light truck market (80-85% of trips and passenger-miles). Uber/Lyft (plus traditional taxis) is already much bigger than public transit (~2% vs ~1-1.5%) and still growing and with what should eventually be a much lower cost structure robotaxis should greatly expand this. In other words robotaxis like Tesla will likely be much more scalable than public transit.

[bgnn]

This is so wrong outside US.

SE Asia and Europe is proof of public transport being viable.

[spikels]

Not as familiar with EU statistics but for shorter trips (under 300km) public transit is well under 10% of trips while cars are over 50%. For all intra-EU travel in passenger-miles cars are around 75% while busses/trains of all types is well under 15%. Viable sure, more scalable probably not.

You have numbers for SE Asia?