Why do you assume most self-driving cars use Canny edge detection? And even if they did, you can simply have the algorithm choose the higher threshold (with some other sanity checks, suck as are the lines the expected distance apart) and ignore the lower threshold.

The algorithms for lane following are quite a bit more sophisticated than that though. Here's a paper from 2008, and there are other approaches as well.

http://www.vision.caltech.edu/malaa/publications/aly08realti...