Well the assumption of supply adjustments to meet demand in real time that is given for Surge Pricing is just unrealistic. A driver must make a commitment (hours or days before) to be available to drive at a given time. Of course they have no idea what the surge multiplier is, so they'll have to guess. As a result the number of cars on the road is driven by the _expectation_ of the multiplier, rather than the actual multiplier.
This affects the demand side too: people remember stories of people getting burned by huge surge multipliers, and as a result adjust their behavior (being more willing to call a normal cab, driving instead of taking a cab). Here again the actual surge multipliers matter less than the expectations. By providing reasonable estimates, they could set surge multipliers that would ensure a high supply of drivers and demand for them, instead of having the curves moved out of whack by overestimation.
This affects the demand side too: people remember stories of people getting burned by huge surge multipliers, and as a result adjust their behavior (being more willing to call a normal cab, driving instead of taking a cab). Here again the actual surge multipliers matter less than the expectations. By providing reasonable estimates, they could set surge multipliers that would ensure a high supply of drivers and demand for them, instead of having the curves moved out of whack by overestimation.