Highlighting the current limitations of self-driving vehicles, Volvo North America CEO Lex Kerssemakers and L.A. Mayor Eric Garcetti engaged in a somewhat heated exchange of words during the L.A. Auto Show this week when Volvo’s new autonomous prototype vehicle couldn’t find the boundaries of the roads it was on and refused to drive.

Kerssemakers told Garcetti L.A. “needed to paint the bloody roads.”

The difficulty self-driving cars have with anything but optimal road conditions highlights an extra cost associated with the technology. While people can make do with any road a vehicle can physically travel over, self driving vehicles require high-quality, predictable roads with adequate markers.

Self driving cars currently do not do well in weather conditions such as rain and obviously snow for the same reason.

Around 65 percent of America’s roads are not optimally maintained, according to most estimates.

However, self driving technology is adapting by using new ways to understand their paths, such as radar and Lidar, which send out radio waves or light pulses to orient itself through triangulation.