With regard to the last few comments, as you know the IJF itself has undermined the principle of its own definitions by not freely letting newaza or katame-waza go on. Most proficient newaza specialists (or BJJ-ers for that matter) know very well that you have to search for openings, and that overall the pace of newaza is slower than that of tachi-waza. Newaza under IJF rules has been emptied as a concept and evolved towards being understood as merely katame-waza.
As referees, no doubt, there are situations we hate. Matte has always been away to avoid things we hate. Why do referees avoid situations they hate:
1. because it is not fun to goof and cause the wrong person to win due to your own mistake.
2. because referees just like many jûdôka who are obsessed by dan-rank, are obsessed by getting referee promotions.
3. because you may be evaluated during the contest, which adds to the stress factor and you do not like being humiliated in front of the other referees by a more senior referee.
In the 1970s, stepping out of the red border when not in action or when interpreted as running away from the fight or even when stepping out to attack was keikoku. During the 1978 Helsinki European Championships Van De Walle lost his contest even though he had a scoreboard full in his favor, because he performen te-guruma and meanwhile supported himself by placing a hand on the tatami outside of the red border: result keikoku and loss.
In the 1981 Maastricht World Championships facing Khubuluri he was leading and on the road to his first world title. Then he attacked with tomoe-nage, a real attack. Because more than half of his body was outside of the red border, it was consider 'out' and the referee interpreted it as "running away", which it was not, result: keikoku. Try to catch up when you're keikoku behind against a top-elite fighter in such a contest. Result he lost the gold to Khubuluri.
The incident grew to proportions nearly as big as the Shinohara/Douillet cock-up. So what do you think the effect of that was on referees ? No one as a ref. wanted to end up in such a situation, thus we increasingly started calling matte when we things started getting tricky. The IJF then changed the rules to stepping outside of the border being penalized only with chûi rather than keikoku, but still considerable because if you got a no-activity warning, you were close to be behind with keikoku again. Initially insufficient activity got you a warning before it was changed to direct shidô.
There are various similar situatios which refs dread, and under the current IJF rules, well ... you know.
The "apparent result" is something you learn with experience but not always so easy to express in words. During my first jûji-gatame injury, the following happened. My opponent during the final of the nationals caught me in jûji-gatame. No doubt that the armbar was effective, but I refused to tap out. Yes, we were idiots, but that is how it was. I would not be humiliated in front of the entire audience by having to tap out. If I tapped out, it was my fault I lost the fight, and I could not say I would have given it all, and moreover, I remembered all I had to do to get there. There are pictures still where you can see the ref with his arm already still bent but lifted to call ippon, but it did not come. Slowly I was able to get on to my knees, and finally stand up with my opponent still hanging on my arm, the armbar being effective, but my opponent being unable to dislocate it (: the only 'result' that is meant when in the definition of 'apparent result'). So yes I ended up with seriously torn tendons and excruciating pain and had to finish the match on one arm, and in the end lost the match nevertheless. The issue nevertheless is the "apparent result". The referee acted correctly and finally had to call matte since my opponent was not able to break or dislocate the arm, and I was not prepared to tap out. Simply calling ippon would have been a wrong decision there at that level. The point is that with regard to the immediacy of the result considerable time lapsed, but if when I was already standing up and just before I lifted the opponent off the ground he would have succeeded to dislocate my arm or I would have tapped out, it no doubt would have been ippon. The ref. was also correct to let the armbar go on that long. Obviously I would have been a lot happier and healthier if he hadn't, but in that case my opponent would have been unfairly treated.
Indeed, shime-waza usually is simpler, but not always. I mean usually, because we don't have an extra bypass that provides our brain with oxygen while we are being choked, but there are occcasions such as jûji-jime from behind the neck but with tori holding on to his lapels with the fingers. Essentially, tori may be doing everything correct, but the choke is in limbo and cannot force uke to tap out. In that case, matte is proper. After all, "apparent result" is not really merely applying a choke that technically looks like a textbook example, but "apparent result" refers to choking with the objective of choking, namely achieving unconsciousness" being imminent. However, even then it is possible to come up with scenarios where matte might be wrong, such as when renraku-waza is applied from one shime-waza into another or in to another katame-waza, or the shime-waza which is not effective being applied while osae-komi is also being applied meanwhile applying both, or uke who is lying in osae-komi applying the shime-waza while tori is holding him in osae-komi. So yes, complicated scenarios can occur, and it is understandable why refs. may want to avoid these, even though at one point the IJF strongly reminded us to not (or no longer) call matte just because a situation was at risk of something ... Then again, the IJF had easy speaking since they were not being evaluated or were not looking for a ref. promotion. It is for the same reason that those in charge are typically in a far more comfortable situation when it comes to this than the rest. That probably too contributes to so much of the mess we have.