Just wanted to chime in with the frustration. I'm doing very few in-vehicle installs these days, but until a month ago, I was doing anywhere from 5-20+ on an average week. I was in a program that had one harnessed seat, one booster, and one low-birthweight infant seat for use in certain situations. That was all we stocked, and it was a low-income program, so families coming to us couldn't just pop out to BRU and pick out a Radian or whatever.
The "rules" that keep cropping up... In the real world, they don't work. When I have a mom roll in with her 6yo in a harmony backless and her 2yo in an old school Scenera, I will gladly tell her that the Snugride we're replacing really shouldn't have been center LATCHed in her Accord. And I'll suggest that we put the 1yo into the 2yo's Scenera because the Titan65 I have will last longer than the Scenera for the toddler. But when I go to put those kids in the car and find belts that come out on opposite sides, or that I can only fit the booster in if we slip it under the side of the convertible... That's how they'll leave. Because what are our options? Put that 2yo in the front seat, untethered? Tell her to leave the 6yo without a booster?
MACPS is a great organization - I love that the manufacturers are all coming together to give harmonized statements so that we have a better global understanding of passenger safety. But when we have these random, minute, NOT CONTAINED IN MANUAL OR CURRICULUM guidelines, this is an issue. As a technician, I have time to do one of two things: I can stay online and stay up to date on every random rule and exception and quirk, or I can get out in my community and help families with car seats. But what good is one without the other?
To the manufacturers of vehicles, of car seats, and the writers of curriculum, I say this: if it's important, put it in your manual. If it's not in the manual, it doesn't exist. Because, sure, 2% of techs are on Cso or in tech talk or whatever. But when I go out to a rural county and work an event with all five of the techs in that county, when I start spouting rules that are from some tucked-away document that no one's ever heard of, one of two things happen - either the techs write me off as nuts, or they give up and go home. And then instead of having seats that are installed tightly, with locked belts and snug harnesses, that might violate random rule #108, we have families with no access to technician resources because they have all given up - because what's the point. They cannot stay cutting edge up-to-date on these random bits, and at this point I feel like getting "the big stuff" right isn't good enough anymore.
Which is insane. Car seats, used at all, save lives. Car seats, properly used, save more. And optimally used, they save more still. But if we can get a tight installation and a tight harness, guys, WE WIN. If a .75" overlap of seatbelts precludes these things, then maybe we need to rewrite the curriculum to reflect that. (Weight limits on LATCH cropped up - it really WAS that important and now it's widely known. Are the overlap rules? If so, they need to go into wider circulation, too.)