I thought so too originally, but the linked video shows a few reasons why it wouldn't. Autonomous cars have the same space inefficiency per passenger (in some cases worse) as driven cars. They still need a place to charge, but that can't be only in non-congested areas because people wouldn't want to stand around waiting 12 minutes for their pickup. If they don't use parking they'd spend their day roaming around, causing traffic like 24/7 taxi drivers waiting for an order except taking up road space.

And watch with Elon Musk in government and schedule F employees, safety will be the nth priority behind profits for Tesla.

As the video points out, what you're describing is very similar to what was said about Uber & Lyft. At first glance, a cheaper, more available taxi service seems like it should reduce road usage. However, that assumes car trips are replaced by rideshare trips. In actuality, when Uber & Lyft have entered a market, it has resulted in increased road usage. This is because of induced demand, and if rideshares are replacing another form of transportation, it's usually public transit, walking, or biking, not driving.

Please watch the video as it provides reasons as to why autonomous cars will reduce safety and increase road usage. I could however see autonomous vehicules being useful for long-haul cargo transport, though trains might be a better choice.