I don't know if they are stupid, but they are definitely reckless bullies. I am always extra careful when I come across trucks on the road.
You should use your common sense and get yourself a career that doesn't require you to deal with stupid truck drivers.
The truck drivers i know are smart, speak english and several have high-end degrees. They have a ton of kids tho...
It is clever of them not to listen if they don't understand English. I dispute that all truck drivers are stupid....<br />
However, under a capitalist society it we are rewarded to make as much money as we can with our skills/time so that we can use that to support ourselves (etc.). So if one can drive a truck with very little intelligence, then that is what people with little intelligence will do (as long as they have enough intelligence to take advantage of the opportunity). They would be stupid (or more so) if they didn't.