That may be the case but my point was that hopping off-the-plane in SE Asia and grabbing a cab is not such a routine occurrence for most Westerners as to be a viable business model for VC-backed companies.
Outside of america, how many people routinely travel by taxi/rideshare/etc. In my experience, most locals take public transport. The international businessperson (on expenses) is a large market -- look at the size of the market for hotels, airlines, etc.
The one place I see taxis in use as mass transit by normal people is Singapore, where they are mostly ubiquitous (in the centre) and cheap. Even then getting a taxi if you're a couple of miles out (say in Hougang, where I spent a month) is hard work - Uber wasn't perfect but it worked well enough.
China: taxis and ride sharing is extremely popular with the middle class. "Most locals" do take public transit, but given 10 million people in Beijing alone, some is still a large number.
Most developing Asian economies have thriving taxi industries where taking a taxi isn't considered a niche service/extreme luxury. Heck, taxis were never that popular in America, nowhere near how they were popular in China in even 1999.
I took a taxi in beijing a few years ago. Was in it about 40 mintues, traveled about a mile. Paid the driver a 20 Yuan note (about $3) and went into the hotel. Driver came running after me with 8yuan in change.
I assume taxis are still insanely cheap, and traffic is still insanely bad. Last time I was there I took the train and metro. I do the same in Moscow - why sit in traffic?
Have you seen Beijing's subway? I travelled to and from work off hours, so I would go to work around 6:30 and come home around 3:30-4, taking the taxi to and from each day was totally feasible and affordable. Even in peak traffic, you still might win in a taxi vs. a subway depending on where you are going. When the whole system melts down, sure, take the subway as a last resort.
I took Beijing's subway around quite a bit last summer. At least where I was going, it seemed preferable to sitting in traffic. Payment seemed easier to navigate as well compared to the prior time I visited. I'd have said it was a pretty decent subway system overall.
I think if you are exploring the city during rush hour, sure subway makes sense. If you have a fixed route you go between everyday and know when the traffic ebs and flows, taxis are much more convenient. If you are out at night after rush hour, then taxis are the obvious choice.
Beijing's subway system is crowded, some routes are super crowded (line 10, ugh), interchanges can be long and windy, and can also have their own long lines (e.g. transferring at dongzhimen during rush hour). There are a lot more lines definitely then when I started living there (2007, line 10 didn't even exist yet), but there are very good reasons didi is still extremely popular.
There are many western cultures who travel more than Americans. Much of Norway migrates to Thailand during the winter, for example. As for viability, you might be right, but global ride sharing services have been a game changing feature for me. Even at a premium, it would still be a useful service.
The one place I see taxis in use as mass transit by normal people is Singapore, where they are mostly ubiquitous (in the centre) and cheap. Even then getting a taxi if you're a couple of miles out (say in Hougang, where I spent a month) is hard work - Uber wasn't perfect but it worked well enough.