Mistakes could have happened, unintentionally, or some judges saw things that others didn't depending on where they sit.
Re:SlSt2 that Chan had in his SC SP, given that a fall is not an automatic -3 GOE, the judges certainly was within in their rights to consider mitigating actors in diminishing the impact of the falls. In fact, judges are instructed to consider the element as a whole and score the element as though it's error free before considering the impact of the error. So say a judge would have given Chan +2 without the mistake, then +2 - 3 = -1 In Step Sequences, more than jumps, and we see it in Ice Dance mostly - falls don't and shouldn't result in automatic -3. Crone/Poirier and Davis/White are examples of that. Why? Because unlike jumps, which lasts about 1-2 second or so in the air, + maybe 2-3 seconds on landing, a step sequence is a lot longer and relatively, a fall on a St is a much smaller part of the whole element vs. a fall on a jump. Hence, it is not a surprise different judges come up with more varied GOE when an error happens on a St. In my opinion, those judges who gave Chan -3 on the SlSt erred by not considering the element as a whole since it was unlikely the element would have scored 0 GOE without error.
Granted, not everyone look at a same thing in the exact same way, hence there are usually 9 judges, not just one person. However, so long as they are following the correct underlying principles. does it really matter there are reasonable difference in opinion?