I’m not the person you were talking to but I’m happy to spoon feed you an answer since it was so trivially easy to find: Behold, a normal sized car with a large carrying capacity and a good safety rating.

Smart gets a 5 star crash rating and is smaller than a. Kei truck. It can be done. Get Smart to make a pickup, literally just stick a bed on the back of the thing.

I’m not saying at that size! I’m saying that whatever size increase you need to make a reasonably safe pickup would be closer to the small extreme (the Kei) than the large extreme.

because it can’t be done at that size

it literally can be? You just don’t need to crash it into a freight train. The reason most large vehicles are so much safer is because you are significantly more likely to kill the other person in a car crash, especially if they’re in a smaller car, and if they’re not, then both you and the other party will experience significantly more impact forces compared to using a smaller car, which fun fact, makes surviving crashes a whole lot easier.