Quoted from vid1900:Pinball cabs are just made of junk.
You always see scraps of other games cut up and used as braces.
You even see things like brick pattern MDF used as bottom panels.
At the time Bally was making EFTLW they had cheapened the cabs up to the point of using particle board instead of plywood and T-molding rather than joinery. If CCC said "hey we've got a bunch of miscut bottom panels, if you allow us to use those, we can save you $1 a cab", I'm sure Bally said that was a great idea.
Inside my Special Force you can see artwork from atleast one other game where they reused cabinet wood.