Smartphone apps and GPS (global positioning systems) have opened new models of informal transit.
Companies like Lyft (United States) and Uber connect potential riders to part-time drivers through apps and collect fares by smartphone.
Many services use the same technology to drop off bikes or scooters at rider-selected urban locations. Riders pay by smartphone and leave the bike or scooter where the company can pick it up using GPS. Other companies provide stations that rent bikes for urban use.
Examples from the developing world include Didi (started in China now with services all over the world); Mobike; Ofo; Grab (in Southeast Asia); Go-Jek (motorcycle taxis in Indonesia that use apps and compete with informal motorcycle taxis)