It all comes down to the fact that referees at this level are more about selling the game to spectators than actually refereeing the match. The idea that people didn't pay money to watch a referee send a player off.
Which is where the biggest problem with this game is - nothing is ever the fault of the players.
No different in the HAL. And it just means that when players are booked for dissent, or heaven forbid, sent for OFFINABUS, it's always ridiculously inconsistent.
And I know our top referees are blatantly ignoring the instructions the rest of us are given - I was once at my local seminar (a few top-flight referees in my association), and one of the coaches from the top level were there, saying we're all expected to crack down on highly visual dissent - you know, flailing arms while whinging about a decision, that sort of thing, and even the professional refs are being told to do this. Murmers of satisfaction all around. That very afternoon the top referees that were in the room refereed a pro game, heaps of that 'highly visual' dissent, didn't bat an eyelid. But the fact that it kept going across multiple games is what proves that the referee coaches/assessors aren't drawing attention to it.
Then of course, I see the exact same thing at the high grassroots levels, too many refs lack the balls to pick up on blatant dissent/abuse. But I blame the assessors.