1. what "certain things"?
2. adjustable racks take seconds to adjust between classes, most weight class competitors are round the same height
3. don't want to pay for equipment so they place a hundred pound twink on the end of a bar with 250lb on one side? Law suit anyone?
4. want the dangers of lifting? don't talk daft, can you show me where these people are arguing to be placed in danger?
1) Side Judging is the main thing. The side judging is one of the most important positions in powerlifting. Whenever there is a close call on a lift, every lifter wants to know what the side judge saw. With a Power rack, the uprights, plus the safety bars can be right in the way of what the side judge is look for. Things like hip crease, etc.... It might not be a huge thing with the really deep guys, but with the larger lifters, and the guys that do just enough to win, it's important to get the best side judging you can. With human spotters, you can adjust them to get the best view.
2) See above. It's about the working with what's best with the judging, and the lifter. With certain lifters, it's not just a height thing, but how they set up the lift. For instance, with big lifters, their grip for the squat maybe all the way out to the bar ends/inside collars. So the safety bars are directly in the lifter's way. Also, sometimes guys use the bottom of Monoracks, and these narrower racks as gauge and some times a brace for the lift. Can't do that with a power rack.
3) The rack used during that meet is about $3000 new, I'm guessing if a rack was designed to fed standards, it would be $5000 or so. Plus extra transport cost, etc.... Most meets are lower budget affairs, most meet directors just aren't going to put out the extra cash, and the IPF, etc.... won't force them because it would cost them money too.
The blame lies with this meet director for not getting the best human spotters he could. While mechanical safety are nice, there are literally 100's of big competition squats that work perfectly fine with the standard 3-5 man spotter teams. The difference is that the meet directors call in favors, offer comps, or just pay to get the best guys there.
4) It's usually not explicitly stated, but read any thread on a real powerlifting board comparing similar lifts done both with a traditional walkout, and without. You'll inevitably, see comments like "Yeah, but that lift had a walk out" or guys will discuss the majesty and toughness of having to walk out a big lift, and how that's missing with these new lifters/feds/monoracks, etc....