I would say it is getting worse. Amongst the many possible reasons I would lay the blame at the feet of us referees.
THAT is exactly my take on it as well!
Travelling to a game a few weeks ago, all three of us in the car (plus an extra we were taking to another game at the same park) I put forward the idea that as a federation we should tighten up and lower our tolerance levels, "You're preaching to the converted mate!" "Spot on Matty" etc etc was the response.
During the game, a very niggly, bad-tempered affair the ref gave two cards for dissent and one for tackle from behind. Had I been in the middle, there would have been at least six for dissent/unsporting remarks!
Another argument I heard after mentioning it at another time, "Ah, well, there'd be too many cards and sendings off"
Well, yeah, I thought, but only for a weekend, or two. By the third they should have got the message and keep their gobs shut!
Problem is, as you point out, there is no consistency between US as referees - and the players will try and push the boundaries every time.
It's something I might bring up at our AGm which is coming up soon.