If you visit capital cities such as Bangkok, Thailand; Phnom Penh, Cambodia; and Hanoi, Vietnam, the first thing you'll notice is how cluttered the traffic is. (I haven't been to Ho Chi Minh City yet, but I hear it's WAY worse). It's a swerving mess of tuk-tuks, motorbikes, and other contraptions which I don't know the names of. Traffic laws are almost non-existent. For example, I've seen motorcycles drive in opposite directions, on the same side of the road. I have NEVER seen anyone get pulled over for speeding, and doubt I ever will. The traffic gets so dense in Vietnam, that motorbikes and people often "walk" together in the streets, swerving in and out of each other without a second thought. This transportation nightmare is mostly due to overpopulation and poor road infrastructure. To put things simply, you have to be a damn good driver to navigate heavily populated Asian cities. Many Americans, even those who are pretty good drivers, would fail at moving around by road here.
I couldn't tell you exactly where the stereotype originated from, but I will hazard a guess. Some Asian Americans who came from places with chaotic traffic, had trouble adapting to the strict, orderly roads in the West. Therefore, a gross exaggeration was born, positing that Asian people don't know how to drive properly.
In reality, it takes great driving skill to cruise Southeast Asian roads. Busting stereotypes while traveling has become a hobby of mine, and I'm glad to rip this offensive idea to shreds. Next time someone makes a comment about Asians being "bad drivers," tell them they should try driving in Vietnam!