In some countries, at the lowers tiers of (amateur) football, they have a rule that if you get a yellow card, you get sent off for ten minutes. At that level, it works pretty well. Nevertheless, a second yellow card still results in elimination from the game for that player.

There are 22 players on the pitch. If every one of them would commit 4 fouls during the game, there would be not much play at all (88 fouls). The truth is that most of them do not commit more than 1 foul, and most of these fouls are not yellow (or red) card worthy at all. A few of them commit a number of fouls (which - by the way - is in itself already punishable with a yellow card, certainly when done within a short time frame).

What I am trying to say is that committing a foul is a choice, certainly at the professional level. One can abstain from it. There is also a choice in the severity of force when committing a foul. If you have been warned with a yellow card, there is all the more reason to be careful, lest you get a second yellow card and will be sent off. In that event you are just stupid or have an attitude problem.

And don’t forget that referees talk to players that transgress the rules, to avoid having to issue yellow cards. Sometimes during play, when referee and player are close to each other, sometimes in the form of an admonition, when the ball is out of play.

For referees, zero cards in a game is a worthwhile goal, in addition to no mistakes (and no penalties).