The problem IMHO is just that you need a different app for each cities cab companies. That's great if you were living in that city and regularly taking cabs. I don't know what the percentage is, but at least for me, I only take cabs when I'm travelling, otherwise I drive my own car. I like having one or two apps, and I don't have to find, sign up for, and configure an app for each city I go to.

Note - this is actually a bigger issue, not one that the cab companies can necessarily fix - but I think PayPal is doing the best here in having a "checkout with PayPal" on random websites and I don't have to do anything but log into paypal. I'm still surprised it seems like no one else is really doing it. I've very occasionally seen Pay on Amazon, but I don't recall if in those cases I still needed to create an account on the website etc unlike the newer offering from PayPal.

Where's American Express, Visa, Mastercard, Zelle, Venmo, Cashapp, etc or even another new offering that just makes it as easy as PayPal does to have your "Pay online / in the app" account that if you do it gives the seller the payment (without exposing your actual card number), and address if needed for shipping?