Delivery guys are covered under general commercial liability policies of their employer. They don't need auto-specific coverage since driving is incidental to the primary business (food prep/sales) rather than the point of the business. In some states, the companies are required to take out additional insurance to cover their delivery drivers, but the policies aren't driver-specific. Either way, the driver is covered by the company, which is how it should be. (Auto insurance policies don't prohibit food delivery employment--only package delivery and passenger transport, as those raise very different liability issues.)

Uber's business is connecting drivers to passengers, and it takes a commission for doing so that is in some cases equal to or greater than what taxi companies collect for roughly the same service. The difference is that taxi companies are required to have insurance, and Uber arbitrages insurance costs and books it as "revenue."