Self-driving trucks are here. Otto, a self-driving truck startup that Uber acquired this summer, shipped a truckload of Anheuser-Busch beer across Colorado. According to Otto’s blog post on the trip, “our professional driver was out of the driver’s seat for the entire 120-mile journey down I-25, monitoring the self-driving system from the sleeper berth in the back.”

But this doesn’t mean the nation’s truck drivers need to start working on their résumés. Technology like this may eventually displace human truck drivers, but the tech is several years away from causing mass unemployment.

The key reason is that Otto’s self-driving technology is initially limited to highways. When the truck reaches ordinary city streets, it hands control over to a human driver to handle tricky traffic situations. This means that even after a truck is outfitted with Otto’s self-driving technology, it will still need a human driver in the truck.

Limited self-driving is still good for business

So if you still need a driver in the truck, what’s the point? The big advantage of the technology is that it could allow drivers to extend their working hours without running afoul of strict federal regulations limiting drivers’ hours.

The rules are a bit complicated, but drivers are generally prohibited from driving more than 11 hours per day or 60 hours per week. Since there are 168 hours in a week, this means that a typical driver’s truck gets used only about a third of the time. On a long trip, a driver will often pull over, park, and spend the night in the truck’s sleeper berth.

Otto’s technology could allow the driver to get a truck on the freeway for a long trip and then hop into the sleeper birth immediately. If the feds agreed to count these rests as off-duty time for purposes of federal regulations, that could allow truckers to stay on the road around the clock until they reached their destinations.

Is this good or bad for truck drivers? It’s hard to say.

On the one hand, drivers could log more miles in the same number of work hours, so the first drivers to adopt the technology will earn more. Otto is planning to sell its technology as an add-on kit for existing trucks. And many drivers own their own trucks, so Otto’s technology could help them recoup the cost of their trucks more quickly.

But as the technology becomes ubiquitous, shipping rates will inevitably fall. In the long run, that could leave drivers worse off than before — working even longer hours without higher pay.

The larger worry for drivers, of course, is that the technology will eventually advance enough that trucks can drive themselves on city streets too, rendering truck drivers completely unnecessary. But that’s a much harder problem, and it might take a number of years for the technology to evolve from freeway-only driving to rendering drivers totally obsolete.