Sure, but how does this system work? Especially with newer services, like ride sharing, where people use personal vehicles to transport people within these areas?
You could require them to register as commercial vehicles. You can enforce using physical barriers or punishing fines/use fees for people that don't enter the area with a fare. Taxis can only go in certain parts of airports, rideshares have designated pickup zones, it seems to work fine. Or you just say that one of the downsides of being a part time driver that isn't part of a regulated fleet is that you don't get to congest downtown areas.
In Granada Spain I noticed that certain parts of the old city had physical barriers that could only be passed by a vehicle with the right NFC pass. Generally taxis, busses, and a few private cars that seemed to belong to people with property in the area. It made it very pleasant to walk around the old streets without having to suck down exhaust fumes of idling cars.
As you noted, Uber is a newer service, plenty of people happily lived their lives before it existed.
As an example, this sign [1] is at the edge of Copenhagen's main pedestrian shopping street.
The international symbols show it's a pedestrian zone, and there's a rule of no stopping from 11-04 (no stopping meaning not even any loading/unloading, a stronger restriction than no parking.)
The text says "Residents excepted" (under the graffiti/sticker) and "Goods vehicles excepted 04-11" (so deliveries and rubbish collection in the morning) on all days including Sundays and public holidays.
50m down the cross-street on which the StreetView car is driving, there's the standard sign for no motor vehicles [2], and the text underneath says "Except for business" -- so this street can be used all day for delivery vehicles etc.
Both signs are enforced similar to parking: get caught, and you'll be fined. I'm sure you're less likely to be challenged if you're driving a van with "Plumber" written on the side, but it shouldn't matter.
No doubt it's more complicated in cities where this is enforced by cameras.
(In addition, the pedestrian streets are mostly conflicting one-way streets [3, and do a 360°]. No problem for a delivery, but useless as a shortcut.)
On a more serious note, ride sharing services are considered as taxis which are considered public transport and public transport is generally allowed at least on designated roads.
You walk or take transit within that area? In my experience European cities are super walkable within the core, never bothered with taxis or ride-sharing.
In Granada Spain I noticed that certain parts of the old city had physical barriers that could only be passed by a vehicle with the right NFC pass. Generally taxis, busses, and a few private cars that seemed to belong to people with property in the area. It made it very pleasant to walk around the old streets without having to suck down exhaust fumes of idling cars.
As you noted, Uber is a newer service, plenty of people happily lived their lives before it existed.