I don't think its selective enforcement so much as different crimes that can appear superficially to fit the same facts. Filing late because you made a mistake

I don't think its selective enforcement so much as different crimes that can appear superficially to fit the same facts. Filing late because you made a mistake will cost you interest plus possibly a penalty relating to the amount. Tax evasion is a crime which can lead to jail time. The system will decide which one fits better based on your behavior, including how cooperative you are when they investigate it. Just like if you hit someone in the head and they die. Maybe you will get charged with murder or maybe they will believe it is an accident. There's really no way to remove these human factors from the justice system.