There is absolutely a large chunk of the rides-for-hire passenger population that is entirely mercenary in its affections. Some people are loyal Uber passengers or loyal Lyft passengers or whatever, but a lot of people are happy to go where the bargains are.

This, exactly. And more critically, because of the non-mediated nature of the interaction (that is, Uber is an absent middleman for the actual customer experience), drivers themselves can push passengers to other services. For example, a new arrival to the space could offer drivers a promotion for each new passenger-customer they recruit with a code. Driver is driving for Uber, hands passenger a card with the new service info and a $20-off code so they try it. No stickiness at all.

I think you're right that isn't out of loyalty that people use one or the other service. But it's de facto loyalty - also known as (extreme) laziness. Most people are using Lyft and Uber for the convenience. Thus if both are about the same level of convenience they will probably not shop around for a new app even if the competitor has a lower rate. They will go to the Lyft or the Uber app if it is already on their phone. More advanced users will probably have both - but that is a minority of users. So it's critical for one of these two apps to be the first installed on the phone.

I work for Flywheel, a (much smaller) competitor in the same space.

Customers like you describe certainly exist, and may be the majority, but mercenary customers who switch services are a large subset of the total. For example, we don't surge, and a substantial number of our customers report that they only use us when Uber and Lyft are surging.

There's also a time-frame issue here. The number of users who check different services with every ride is low. The number of users who check different services when their primary service is surging is higher. The number of users who are open to occasionally checking out other services if they hear good things is higher yet.

Cost-insensitive users who have Uber brand loyalty may be a large rump population for Uber -- they were the original adopters of the service. But their growth has been in cost-conscious people, and they've been in deep competition for those people, in a price war. Those passengers are a large enough share of their user base that they can't do without them.

Off-topic, but Do you have a timeline for getting into the Boston market, or a suggestion of an app out here? Taxi dispatch is terrible in this city. I was a consistent flywheel customer in SF and loved it.

Sorry, I can't comment on our expansion plans. I don't have any personal experience with the Boston scene, and the value of different apps is often very location dependent, so I'm not sure how the experience will be, but:

Hailo operates in Boston. They use real taxis and are well-established in other cities, probably worth a try if you are looking to replace taxi dispatch.

Thanks for the kind words, and I hope we get to Boston soon and you can give us a try.

Some companies that serve as middlemen seem pretty resilient. For example, ebay and craigslist.

This is because they are natural monopolies.