Robotaxi companies are learning that removing the driver from the equation also removes the person who can enforce basic rules of conduct. As autonomous vehicle services expand across major U.S. cities, operators are grappling with a problem that traditional taxi services never had to engineer around: how to discourage passengers from smoking, vomiting, and engaging in other unwanted behavior inside driverless cabs.

What Happens When No One Is Watching?

Zoox, the Amazon-owned self-driving startup, has served more than 500,000 passengers since launching free rides in Las Vegas and San Francisco in September. That volume of real-world experience has revealed some uncomfortable truths about passenger behavior. The company's engineers have documented recurring issues that are now shaping the next generation of robotaxi design.

"You're not supposed to smoke in the vehicle. They smoke in the vehicle. And they're smoking everything in the vehicle," said Chris Stoffel.

Chris Stoffel, Director of Robot Industrial Design and Studio Engineering at Zoox

Smoking is just one part of the problem. Zoox engineers have also had to contend with passengers vomiting inside the vehicles. This wasn't entirely unexpected, but the real-world data has forced the company to rethink its approach to materials and cleaning protocols. The challenge isn't just about hygiene; it's about making cleanup fast enough to keep vehicles in service.

How Are Robotaxi Companies Adapting Their Vehicles?

Zoox recently unveiled an evolution of its custom-designed vehicle as it prepares to expand service to Austin and Miami. The company has made several passenger-focused improvements based on what it learned from over 500,000 rides. Here are the key design changes engineers are implementing:

• Moisture-Resistant Materials: Zoox is switching to materials that resist moisture and odors, specifically designed to handle the aftermath of smoking and vomiting without absorbing smells.
• Faster Cleaning Capability: Rather than replacing parts after incidents, the new design prioritizes surfaces that can be wiped clean quickly, keeping vehicles operational between rides.
• Nook-and-Cranny Reduction: Engineers are redesigning areas where vomit and other contaminants can get trapped, making the vehicles easier to sanitize.

"We wanted to be able to wipe clean any issue very quickly rather than replace parts," said Stoffel.

Chris Stoffel, Director of Robot Industrial Design and Studio Engineering at Zoox

Zoox's vehicle design is already distinctive; it features two rows of face-to-face seating for four passengers, sliding doors that part in the middle, and no traditional driver seat or steering wheel. The company builds these vehicles in-house, giving it full control over how to address real-world passenger behavior.

Is This Problem Unique to Zoox?

Zoox is not alone in facing these challenges. Other robotaxi operators are dealing with similar issues. Waymo, Google's autonomous vehicle subsidiary, has had to contend with passengers hanging out of windows, and there have been reports of passengers engaging in sexual activity inside self-driving cabs across the industry. As robotaxi services grow in popularity and expand to new cities, managing passenger behavior is emerging as a significant operational challenge that goes beyond the technology itself.

The problem highlights a fundamental difference between autonomous and traditional taxi services. In a conventional cab, the driver serves as an implicit enforcer of basic conduct rules. In a robotaxi, there is no human presence to discourage misbehavior, and the vehicle's sensors and cameras are primarily designed for navigation and safety, not passenger monitoring. This creates a gap that companies are now trying to fill through vehicle design and, potentially, through other enforcement mechanisms as the industry matures.

As robotaxi companies scale their operations, the ability to maintain clean, functional vehicles while managing passenger conduct will likely become as important as the autonomous driving technology itself. The next generation of robotaxis will need to be as much about passenger management as they are about self-driving capability.