I see 'making driving more accessible' as a flaw in itself. Combine this with slower moving vehicles and the result is gridlock.
I'm going to take issue with this, because that's not how capacity works.
Slower vehicles result in greater capacity, because the stopping distance is smaller. In addition, driverless cars can drive closer together, because their thinking time is much less than yours or mine (or anyone's for that matter).
In general, this whole discussion seems to be stuck in the past, and I don't mean people unwilling to accept new technology, that is a function of humans. Scepticism has absolutely got its rightful place when it comes to new technologies and it's important that these things are discussed.
This discussion just seems to have completely ignored the fact that driverless cars are being live-tested in California in as many situations as can be imagined and are interacting with humans (both those in other vehicles and those on foot) and animals on a daily basis, right now. Driverless cars already drive, under no human control, in small streets in big cities. The Google cars have done fantastically at pretty much every situation they've been presented with (that is, all scenarios encountered when driving around Northern California, including, but very much not limited to the City of San Francisco). Their only accidents have so far been when the human took over.
The barriers now are
a) International legal acceptance
b) How to deal with the very powerful car lobby.
c) How to deal with moral* decisions (ie: if there is no mathematically computable way of not killing someone**, who do you kill? Do you force the human on board to make the decision? What if there is no human on board?)
d) Acceptance by people who want to keep driving.
The "interface" with humans is not a problem and hasn't been for quite some time (since at least 2011, when the first cars went out for test).
*For want of a better word
** Although it is notable that these scenarios would be less likely with a machine driving than a human, because the machine can calculate a lot more things and see a lot further than a human can.