If memory serves me right, I seem to recall that TYSLA's stern ramp SWL is 500MT. Which is quite more than your average car :-) Height and width of stern entry is designed for "high and heavy" cargo, typically project cargo.
"High and heavy" cargo is far more profitable than cars and trucks, although just one or two the interior decks can accommodate such cargo.
These vessels are truly cargo machines, a fact not always realized by everyone. Not much to look at, true, but amazing what they can carry. :-)