Sounds counterintuitive, but I wonder if it's is actually easier to only be a hard-working footballer in the higher leagues than a lower league.
For example as a Central Defender in the Pre Pep days 'all' you had to do was consistently be in the right place, win tackles and headers, and pass a simple pass or belt the ball down the ground. The players around you are not making as many mistakes that you need to clean up. (Yes I know defence is a skill)
In a lower league at Centre Back, you have players around you making mistakes, forcing you to play differently, and needing you to be able to to more things to get the team out of trouble.
For clarity, what I am suggesting is that as you become more professional and play in better quality teams, you can specialise, and don't have to be expert at everything.
I like the idea. In practice the introduction of the orange will reduce the numbers of times a red card is issued, as the referees will have a mechanism to punish a team a 'little' bit without altering the entire game. If this was brought in red cards would only be used for clear intentionally dangerous tackles, or clear fouls to stop a goal scoring opportunity.
The comments here are also why the referees are on a hiding to nothing. Some of you want subjective refereeing, but will cry when the 'subjective' reason does not go your teams way, and will find all the other examples where the foul was/was not called. Others wants refereeing to to letter of the law, but cry when this goes against your team (eg the Curtis Jones tackle).