As a taxi service, the unit would have to travel to the client, do the client's run (repeat those two steps if possible), then return to base where the batteries can be swapped out, all while maintaining some degree of emergency reserve. I'm not sure how useful it would be for a taxi service if it only had an hour or two's endurance.

If the batteries can't be easily swapped out, then there's quite a bit of downtime in charging as well.