To me, at least, this assertion requires some substantiation

Then let me invite you to come visit my city, Vancouver, the last major city in North America where ride-share isn't available and taxis are the only game in town.

First, taxi regulations stipulate that taxis get to charge a flat-rate tariff on every ride. They have to/get to charge this. Whatever this tariff was meant to accomplish, it incentivizes taxi drivers to ignore their dispatcher when taxis are in high demand (like on weekend evenings) and only pick up off the street for short hops around downtown. If you need a trip further out (say 5 miles), forget about it - you'll wait for hours before you can get a cab (I have, on multiple occasions).

Second, taxi medallions are crazy-expensive (hundreds of thousands of dollars) and are a cash-cow for municipalities. They're meant to tie taxi cabs to a local city, but they also make elastic cab-supply impossible - you can never have more cabs on the road than you have medallions and because the medallions are so expensive they need to be amortized with constant use. That incentivizes everyone to have far fewer medallions than the industry would need to satisfy demand during peak periods. The most efficient deployment of medallions for a taxi company is to have enough medallions to satisfy minimum, not peak demand.

And don't think that medallions will guarantee good local service - just because a taxi company has a medallion issued by the municipality that you live in doesn't mean that they can pick you up and drive you home. I live in Burnaby (city next to Vancouver) where Bonny's Taxi has a legally-granted monopoly, but if I'm downtown (which is in Vancouver) I can't call Bonny's to pick me up - medallions regulate pick-up, not drop-off.

And even if you manage to flag down a cab on a busy night, they'll quite commonly flat-out refuse to take you anywhere other than downtown. They're barred from doing this, but the industry is self-policing and you can guess how likely it is that a driver would face any consequences for this. Maybe if you film them and post it to social media. But certainly not otherwise. And who can blame them? They have to pay down their medallion-mortgage, and exploiting the flat-rate tariff on short-hop rides downtown is the best way to do that.

Also, carry cash. Many taxi drivers will insist on cash. "Oh, my machine is broken. You need to pay with cash." Again, they're barred from doing this, but again, the industry is self-policing and you can guess how often complaints lead to consequences. It still happens all the time.

And because these are a great bunch of guys, their industry spends millions lobbying the provincial government to stall legislation that would allow ride-share in Vancouver. British Columbia went through a period in the 70's where it was indistinguishable from a Soviet republic with a planned economy, and implemented socialized car insurance. Everyone needs to buy basic liability auto insurance from our govt car insurer (at about twice the market rate in other provinces), and that insurer has simply refused to insure ride-sharers. That's been a far more effective barrier to ride-share than has existed anywhere else that I'm aware of. And the taxi industry spends aggressively to make sure that that doesn't change.

Also, while taxi regulation is pretty corrupt, well, Uber is maybe not the poster child we want for how unregulated companies are gonna do better on that front.

They are exactly that "poster child". Uber at their very very worst is better than the taxi companies and the taxi industry in a city where ride-share isn't available.