They can hypothetically be packed closer together, however: - What level of reliability is actually feasible for such a scheme? If you don’t have 5 9s, are you

They can hypothetically be packed closer together, however: - What level of reliability is actually feasible for such a scheme? If you don’t have 5 9s, are you going to be causing catastrophic accidents? Is that level even enough? Even with near instantaneous reaction times and perfect judgement vs humans, you’re still limited by basic physics/stopping distance. - cars still take up physical space, no matter how close the cars get you eventually run into a flow rate problem. With the addition of self driving cars deadheading to pickups, you’ll also have added traffic volumes from entirely empty vehicles.