The random studies that come out on carseat safety usually indicate that MOST families don't have their kids in right.
HOWEVER... cut your friends some slack. Most of the time when we take pics of our kids in car seats we're not actually moving but are in the process of getting in or out. <laughing> I actually had a blistering slam from someone calling me a bad mum for allowing my son to sit on my lap and "drive" the car in a picture. We were parked. But I got chapter and verse in any event. As in ANY time we were physically in the car kiddo had to be strapped in correctly. Um. No. Whist DRIVING one needs to be strapped in correctly. If one is taking pics while driving then the parent isn't strapped in correctly, either. Turning around in your seat (as a passenger) negates most of the good of being belted, and obviously, the driver should NOT be snapping pictures of the back seat, but paying attention to the road.
Also... unless you duct tape them so they can't move... toddler move straps and buckles around a LOT. It's something of a constant "Put that back on your hard parts." or "PUT your arm back in this instant!" comments coming from the driver looking at the toddler in the back seat.
I also know many parents who have turned their car seats fwd facing PURELY for the fact that when they stop the car, they find their child half out of their seat (manipulating the straps in their rear facing seat). So they don't even know to snap at their kids (errrr.... tell them nicely) to fix the durn strap... or to pull over and rebuckle them. Many that have had this problem have taken photos of their backward facing child to show police & or family if questioned as to WHY they don't have their child rear facing. ((Even the little mirrors don't work in most, much less all cases... because they only show so much, and because some cars don't have the right angle to mount them to show ANY)).
In the "slack" category... while many people are idiots, and many more just ignorant... many VERY conscientious people just have to follow different rules. My son was turned around at a little over 6 months because he outgrew rear facing seats. His shoulders were a couple inches over the highest hole, and we had the biggest infant seat at the time. Same problem with the 5 point... we had to go to shoulder straps under 1 year. NOW they have seats that can go backward past 30lbs, and 5 points that MIGHT have fit him to past a year... but at the time, the SAFEST thing was what we did. With a note taped to his seat by our local seat inspector at the Police Station exempting us from tickets, because to follow the letter of the law would have put our son in great danger.