Except then everyone gets upset. Look at the aftermath of the 2006 World Cup, where referees actually enforced the LOTG properly: A ton yellows, leading to multiple suspensions for high profile players, and red cards, leading to suspensions of high profile players. Plenty of matches had multiple yellows and reds, USA v Italy finished 9v10 and the Netherlands v Portugal had 4 reds and 16 yellows. What happened? Did players change their behaviors, did everyone adjust? Heck no! Everyone complained endlessly, including FIFA, and they started to force referees to handle things differently.