If these 18-wheelers are so heavy and unwieldy, why aren't drivers more careful?

A: Quite often, the drivers of these large trucks have delivery deadlines to meet. Many times, there are financial incentives for beating the deadlines. Consequently, many truck drivers will break the rules by driving too fast, driving longer than they should before resting, taking short cuts to bypass heavy highway traffic or construction zones. In some cases, driver neglect can lead to mechanical and technical breakdowns.