They need to spin up marketing in each locality, which is both costly and requires nuance with local colloquialisms and existing market forces (e.g., knowing what ITP and OTP mean in Atlanta, or the huge taxi market in NYC). It's probably the hardest part to scale.
They also need local support infrastructure. Lyft actually does an in-person interview with every driver, which requires a human being there. They have at least re-used resources by promoting certain drivers to a higher level that enables them to run these interviews. But bootstrapping that infrastructure requires some effort.
Between the costs, the marketing efforts, and the support infra, it's not as easy as just flipping a switch.
They also need local support infrastructure. Lyft actually does an in-person interview with every driver, which requires a human being there. They have at least re-used resources by promoting certain drivers to a higher level that enables them to run these interviews. But bootstrapping that infrastructure requires some effort.
Between the costs, the marketing efforts, and the support infra, it's not as easy as just flipping a switch.