re: #87 Learned Mother of Zion

The thing that boggles the mind is the statement by one of the rabbis from the Orthodox Union (OU) interviewed that they can consider something kosher even if it has 1/60 by weight nonkosher ingredients, but if something has even a particle of chametz, the entire item is chametz:

Rabbi Menachem Genack, the rabbinic administrator of the Orthodox Union, which certifies foods in 83 countries, explains that the rules forbidding chametz are more severe than for nonkosher foods like pork. Jewish law tolerates some contamination of kosher food, as long as it does not exceed one-sixtieth of the total consumed; with chametz, even the slightest speck renders a dish inedible.

I wonder where that distinction comes from, and with technological advancements, is it even possible to render something truly chametz free - after all microscopic particles could show ongoing particles. Why do we not consider the same rules for chametz as we do general kashruth? /going on a 4 questions rant…