Not uncommon in car audio.
a lot of foolishness is common in car audio.
me and a friend once opened the door panel of his Nissan Maxima with Bose system to find out why it had the classical "no highs" sound Bose is famous for and there was a tweeter inside the door
it was literally inside the door - it wasn't up against the grille.
if an OEM would do this imagine what DIYers do in Car Audio.
in my experience PROSOUND ( and by that i mean PROSOUND not to be confused with PA ! ) is the ONLY area of audio where people have some semblance of a clue of what they're doing.
a typical prosound systems costs about $2 million versus about $20,000 for a typical PA system and $2,000 for a typical hi-fi system.
only prosound systems are designed by people with physics PHDs - everybody else just throws stuff together and hopes it will work.
Studio Monitors are in 2nd place after Prosound for the average IQ of people designing them.
DIY Car Audio is at the very bottom of the food chain consisting mainly of illiterate 20 year olds.