Side gaurds

Probably because California would throw a fit that this interferes with their side skirts? Besides it's well known what happens when a car runs underneath the mid-section of the trailer, but the guards are not going to stand up to most of these T-bone type crashes that do occur, anyway. This is not so much about safety as a way to spur more economic development and extract more cash from the trucking companies. Some welder/fabricator really had some political connections.

The mean average height of european vehicles is significantly lower than the mean average height of American vehicles.

 

Dont give them any ideas.

 

because we're not in Europe.

 

Helps to thin out the herd of morons trying to "shoot the gap" underneath your trailer.