In principle the driverless cars are more able to organize fleeting, operating in a way that's not actually practical if you don't share a single guiding directive.

I don't know that you'd ever see this in practice, but it's much more practical in theory for almost identical machines running the same software than for a bunch of humans in a variety of vehicles who've maybe only half understood how to do this.

Also, for this specific problem we know humans are idiots. They should all be driving an agreed route to the agreed evacuation point, but some real humans will decide they know a shortcut, they want to drop past Jim's place, or whatever. Just as there's a difference between what the protocol says happens when you have to abandon an aircraft on the tarmac versus the reality that people will decide they want to self-evacuate and they need their carry on bags and chaos ensues and maybe people die.