I mean, if taxi companies could build their own Uber in house I’m sure they’d love to and at least take some customers from Uber itself.

A lot of startups are middlemen with snazzy UIs. Middlemen won’t be in as much use in a post AI world, same as devs won’t be as needed (devs are middlemen to working software) or artists (middlemen to art assets)

But it's not technical, it's due to uber having spent incredible amounts of money into marketing.

It is technical :-) The Uber app is a lot more polished (and deep) than the average taxi app.

That's why you use Uber because the app has more depth and is more polished?

Most people use it for price, ability to get driver quickly, some for safety and many because of brand.

Having a functioning app with an easy interface helps onboard and funnel people but it's not a moat just an on ram like a phone number many taxis have.

No, Uber works nationwide but you'd have to download a Taxi app for every place you went and ... etc.

The economies of scale is what makes companies like Uber such heavyweights at least in my opinion

Same with AWS etc.