Shippers use brokers because they don't want to be hassled with setting up shipments. They just want to make a phone call and have someone else find a truck and manage the load. That is what the brokers get paid to do. They have to answer the phone 24/7. Some brokers don't even have a life. You might spend several hours brokering a load, monitoring the truck, and doing paperwork. It might just take 15 minutes to book the load, but that is only one of many parts that the broker has to deal with. Most drivers hate paperwork. They just want to drive. I had to pull teeth to get POD's from some of my drivers. How would they handle an Uber type system? Will they pick up on time knowing no one is watching them? It would be a very chaotic situation.