A way to reduce the number of cars on the road in a small community (less than 50,000 people).
What if the community was divided into high volume destinations, such as schools, shops and business areas. Each section would be assigned a color. The objective of the divisions should be to define areas that are small enough to walk within, but large enough to include a good variety of products, services and homes.

Drivers that drive to particular sections frequently and are willing to give others rides could get a sticker from the town. This sticker would identify the car as a Crowd Transit car, It's a limited screening, to get the sticker the driver must show their license and registration.
Around town, in locations where there are people who are willing to ride with others, signs would be posted. The sign would have brief instructions and a color indicator. Riders would need to show identification to get a rider card. This is another limited screening.

The person who would like a ride can set a flag or other color indicator (I haven't figured that part out yet) that lets drivers know where they would like to go. If a driver sees someone waiting, for an area they are willing to go to, they pick them up and give them a ride.
Is this a perfect plan? No. Is it completely safe for all parties? No. However, over time, the drivers and riders will get to know each other so a level of trust will be established. Is this suitable for commuting? Maybe, it depends on how many cars and people are involved.
No one makes any money, with the possible exception of the sticker and sign companies. The idea is to work together to share our limited resources so everyone can get where they need to go.