What Are the Benefits of a Docking Wheelchair Restraint System?

If you're adapting a vehicle so that it can carry someone in a wheelchair, then you need to install restraints. The person needs some kind of seatbelt themselves; their wheelchair must also be held securely in place when you're driving. While you can install a standard restraint system which ties the wheelchair down at various points, you can also use a docking system as an alternative. How do docks work, and what are their benefits?