Unsporting behaviour can already get a player cautioned (and therefore a second such offence can already get a player sent off) and attempting to deceive the re

Unsporting behaviour can already get a player cautioned (and therefore a second such offence can already get a player sent off) and attempting to deceive the referee is literally the first example of unsporting behaviour given in the rules. It's strange that this isn't used more often, particularly in matches where certain players are frequent offenders. In other situations, like putting the ball out so an opposing player can receive medical care, every player understands that this is just good sportsmanship. Likewise no-one criticises a player from that opposing team who gives possession back to the team who put it out when play restarts. So why are players who all respect that tradition OK with people who frequently take a dive or appeal for something they know they don't deserve?