Queuing for ridesharing and organ allocation

 Queues for ridesharing drivers at airports (where some trips are much better than others) lead to lots of rejected trips by those at the head of the line, while they wait for a good one.  This is of course something that also occurs in deceased donor waiting lists.

Here's a paper that tackles the ridesharing problem:

Randomized FIFO Mechanisms by Francisco Castro, Hongyao Ma, Hamid Nazerzadeh, Chiwei Yan

Abstract: "We study the matching of jobs to workers in a queue, e.g. a ridesharing platform dispatching drivers to pick up riders at an airport. Under FIFO dispatching, the heterogeneity in trip earnings incentivizes drivers to cherry-pick, increasing riders' waiting time for a match and resulting in a loss of efficiency and reliability. We first present the direct FIFO mechanism, which offers lower-earning trips to drivers further down the queue. The option to skip the rest of the line incentivizes drivers to accept all dispatches, but the mechanism would be considered unfair since drivers closer to the head of the queue may have lower priority for trips to certain destinations. To avoid the use of unfair dispatch rules, we introduce a family of randomized FIFO mechanisms, which send declined trips gradually down the queue in a randomized manner. We prove that a randomized FIFO mechanism achieves the first best throughput and the second best revenue in equilibrium. Extensive counterfactual simulations using data from the City of Chicago demonstrate substantial improvements of revenue and throughput, highlighting the effectiveness of using waiting times to align incentives and reduce the variability in driver earnings."

"Many ridesharing platforms now maintain virtual queues at airports for drivers who are waiting in  designated  areas,  and  dispatch  drivers  from  the  queue  in  a  first-in-first-out  (FIFO)  manner.4 This resolves the congestion issues and is also considered more fair by many since drivers who havewaited the longest in the queue are now the first in line to receive trip offers.  At major U.S. airports,however, a driver at the head of the queue will receive the next trip offer in a few seconds under FIFO dispatching, if she declines an offer from the platform (see Figure 12).  As we shall see, thislowered cost of cherry-picking substantially exacerbates existing problems on incentive alignment.

...

"During busy hours, instead of accepting an average trip, drivers who are close to the head of the queue are better off declining most trip offers and waiting for only the highest earning trips.  Riders, however, have finite patience, despite being willing to wait for some time for a match.  When each driver decline takes an average of 10 seconds, 2 minutes had passed after a trip with low or moderate earnings (e.g.  trips to downtown Chicago) was offered to and declined by the top 12 drivers in the queue.5 At this point, it is very likely that the rider cancels her trip request, not knowing when a driver will be assigned, if at all.

...

"To  achieve  optimal  throughput  and  revenue  without  the  use  of  an  unfair  dispatch  rule,  weintroduce a family ofrandomized FIFO mechanisms.  A randomized FIFO mechanism is specifiedby a set of “bins” in the queue (e.g., the top 10 positions, the 10th to 20th positions, and so on).Each trip request is first offered to a driver in the first bin uniformly at random.  After each decline, the mechanism then offers the trip to a random driver in the next bin.  By sending trips gradually down the queue in this randomized manner, the randomized FIFO mechanisms appropriately align incentives using waiting times,  achieving the first best throughput and second best net revenue: the option to skip the rest of the line incentivizes drivers further down the queue to accept trips with  lower  earnings;  randomizing  each  dispatch  among  a  small  group  of  drivers  increases  each individual driver’s waiting time for the next dispatch, thereby allowing the mechanism to prioritize drivers closer to the head of the queue for trips to every destination without creating incentives for excessive cherry-picking."