[maccam94]

Think Uber carpooling, minus drivers, much cheaper, and short pickup times. Maybe 6-10 person shuttles instead of sedans/SUVs in denser areas. To a car service, moving an empty vehicle is inefficient and a waste of money.

[masonic]

Keeping an empty electric vehicle in motion all the time is cheaper than parking it, in urban contexts.

[jcranmer]

Because you're not pricing the externalities of having zero-occupant vehicles roaming around streets that are already at or near maximum capacity.