I've only been on Uber for 2 months so I don't know about the past. However, it's odd how sometimes CS adds "toll" and other times "promotional" for the toll reimbursements. I'm thinking that pax doesn't see and isn't charged for the "promotional" amount. Will have to get a ride sometime to test this. Lower fares for the customer! However, if they agree to a toll route, then they really shouldn't be upset to see toll charges added within 24 hrs.
Speaking specifically to this, I can only speculate. First of all, Uber does not seem to enjoy handling any monies which it does not get a cut of (e.g tips).Since tolls come directly out of the driver's toll account, Uber isn't collecting any revenue, so there's no reason for them not to automatically add to the trip, unless they messed up their system, or want lower total fares (by drivers failing to ask for reimbursement).