Not only threat of identity theft...
... name, pickup, dropoff location ...
That could also lead to personal safety risks, depending on how precise that info is. Hopefully it is just the usual lazy-arse data such as "office" or "suburb"* that shows on receipt, rather than eg GPS data. And as Chirgo hints, might be historical as well as current data.
Even name of employer (as cardholder) instead of name of passenger could be useful info to tie to addresses..
* The words office or suburb, not the actual name of the office or suburb. I think these are buttons on the cabcharge box in the vehicle.