Both are without a computer aided dispatcher. The top panel shows a cab queue as found at any major airport. As passengers exit the terminal they go to the first cab in a line of cabs. The rider does not have to wait and the cab goes direct to their destination. This example shows that demand responsive service is possible.
High cost is the obvious problem.
The bottom panel shows how DRS could work, with buses and vans, without computer aided dispatch. These riders would form into lines behind curbside route markers. Buses and vans would wait in queues. A bus would drive to a route marker with a long line and take a group, express, to that destination. Shorter lines would be served by minibus and taxi-van.