Google's self-driving cars are the perfect drivers. As for human drivers ... well, not so much.

Google's cars are designed to do what they're supposed to do. The robocars obey speed limits, come to a complete standstill at stop signs, and always stay in their lanes.

But when a human is behind the wheel, that isn't always the case — and it's becoming a big safety hazard for Google's vehicles on the road.

For example, during a test drive in 2009, one of Google's test cars came to a four-way stop and became completely paralyzed because it couldn't figure out how to proceed when confronted with not-so-perfect human drivers.

According to a New York Times report, Google's car completely froze because other drivers kept inching forward, but the car's sensors kept waiting for other humans to stop completely so it could continue.

Another instance occurred last month when one of Google’s Lexus Autonomous vehicles approached a crosswalk. It began to slow down by itself, as if to allow pedestrians to cross. This prompted the test driver to apply the brakes.

The pedestrian crossed the street just fine, but the self-driving car was rear-ended by a car with a human driver, according to Google’s Self-Driving Car Project Monthly Report.

Google records all of its driving sessions so it was able to see exactly how the accident occurred and calculate what would have happened if the driver allowed the car to continue to operate autonomously. According to its report, if its test driver had not interfered, the car may have prevented the accident because it would've braked slightly less hard and inched a little bit closer to the crosswalk.

"In other words, our software might have created some extra margin in a situation where fractions of inches and seconds mattered," the company said in its report.

"Given the time we're spending on busy streets, we'll inevitably be involved in collisions — sometimes it's impossible to overcome the realities of speed and distance," Google's report said. "This situation highlights what computers are good at. Our software could do the math on many complicated factors all at once — pedestrian speed and trajectory, our speed and trajectory, the other vehicle’s speed and trajectory. And then it could make an extremely nuanced braking calculation and implement a very controlled response, all very quickly."

Google is now averaging about 10,000 autonomous miles per week on public streets, so it's bound to run into some situations where its cars get into accidents, the company concedes. But when it does, it's never the technology at fault.

"In the six years of our project, we've been involved in 16 minor accidents during more than 2 million miles of autonomous and manual driving combined. Not once was the self-driving car the cause of the accident."

While that may be true, it doesn't change the fact that human drivers aren't going away — at least not anytime in the near future.

According to Gartner’s 2015 Hype Cycle for Emerging Technologies report, autonomous vehicles on the streets in any meaningful way are about five to 10 years out. So in the interim, drivers may want to proceed with caution when they spot one of Google's pod-like cars on public streets.

After all, if something happens, it's probably your fault.