You can make your own conclusions how often it happens. Add poisoning eagle through poisoning their prey which also falls under this law and guess how often that happens. Then guess how often it is prosecuted.
Does the pope shit in the woods? I don't monitor 24/7 to check but my logic probably says yes. What's your logic about this law? But don't mistake absence of evidence for evidence of absence.
(Also you can find interesting stuff like https://www.smithsonianmag.com/smart-news/study-finds-rat-po.... Is this illegal? By law totally yes in at least 4% cases of those dead eagles are illegal incidental kills without permit and others are at least disturbance. How many people prosecuted? I count grand total of zero.)
