It's way more difficult from a fleet operational perspective and more importantly, way less profitable. Take LA<->SF as an example. That's about 6h driving, and buses do it for $25-50. That's a measly 7-14 cents per minute. Once you've made the trip, the company has to find someone going the other way. If there's any directional or temporal imbalance, the fleet ends up with a lot of cars sitting idle or driving hours to be useful, further reducing utilization. If the car has an issue halfway, now someone has to pick the customer up hours from a company facility and get them to their destination. All this for pennies. You don't even get an easier problem, because you still have to drive in the city to drop people off.

Compare to city driving: 10 minute drive, $5. That's at least 5x more profitable and takes less capex. Plus, if anything goes wrong, your facilities and backup vehicles are already nearby.