Self-driving cars, for all the limitations they face, are amazing technology. BMW even thinks it'll have a fully self-driving car by 2021. But there are still some very good reasons drivers are a necessity behind the wheel of current cars that feature self-driving tech. Take the below video, titled Autonomous Trap 001. It's a conceptual demonstration rather than a live one – this is a manually-operated vehicle. But it demonstrates a pretty clear concept.

So much of driving relies on standardized symbols that a lot of autonomous driving is about getting cameras to recognize those symbols. However, cars are obeying those symbols in the simplest of terms. Don't cross solid lines. Stop at stop signs. Don't run into stuff. The car isn't making sense of these symbols, it's just matching symbols to behavior. As its cameras look around, it sees a line it can't cross in every direction.

Smart cars are still pretty dumb

The fully self-driving cars BMW is talking about will be able to do anything a human can do, but the automation in stuff like current Tesla cars is pretty limited. Artificial intelligence will be required to bridge that gap. The car has to be able to look at the line around it and figure out that it's not a traffic symbol.

As self-driving AI improves and semi-autonomous cars become more common, finding these kinds of glitches and hacks will be critical to ensuring the safety of the passengers inside these cars. It's easy to imagine other kinds of traps, either intentional or otherwise, that could lock a car in place. Last year, a Tesla car using the maker's Autopilot feature mistook the broad, white side of a semi-truck for a bright sky thanks to a combination of just the right lighting and vehicle heights. The cars need not to just see everything, but to understand what they're looking at as well.