my friends are constantly riding in the back of mine, i've only ridden in them once since im usually the driver, it was actually quite enjoyable and relaxing going 65mph down the highway, it does get awkward staring at someone at a redlight though.
in Texas you're allowed to ride in the bed of a pickup as long as it's below 40mph, so pretty much not the highway, i've had 3 different police vehicles trail behind me when i have my friends in the back, they stare hard, follow for a few minutes, then break away, not sure really why, twice on the highway and once on surface streets...
the brat is a "pickup truck" in other countries but not a "pickup truck" in the U.S. due to the title saying passenger vehicle thanks to the extra 2 seats.
and yes, they have lap belts in the back, mine have been jammed since the day i got it, so they're just decoration, but you're probably suppose to be buckled in due to the fact that it's considered passenger vehicle and the vehicle came with belts originally, it's a 2door car with 2 seats in the back, with a wall inbetween, with the seats facing the wrong way like a 60's Volvo, and then there's no roof, even though thats the least of my worries.... the headrest is more of a backrest, the rollbar is a nice comfortable headrest for breaking your skull open, and relaxing your head to the side introduces you to some healthy slamming onto your skull.
im sure one day i'll get pulled over and i'll have to explain to the judge that this is how the car left the dealership.