Paxs share the car. Payments are all divorced from each other and have no relation between them.
Pax 1 gets quoted X amount for the trip. This amount remains fixed regardless of there being or not a second pax and how much that pax is charged, and regardless of how much the driver is paid.
Pax 2 gets quoted Y amount for the trip. This amount remains fixed regardless of there being or not another pax and how much that pax is charged, and regardless of how much the driver is paid.
Of course, those amount above are calculated by UBER based on the locations for pick-up and drop-off. But that is between UBER and riders.
Driver is paid for the total distance and time as per the local fares regardless of how many pax are picked along the way and how much those pax got charged. This is between UBER and driver.
Driver is NOT paid a % of what is charged to riders.
I am just saying the same thing with different words.
Interesting that passengers in LA ask so much about POOL. Here in Miami they do not ask, they just take them.