||I have noticed that many people don't understand the basic shitah of this website. With your permission, let me clarify something.
Rav Henkin, who together with R. Moshe Feinstein was the leading halakhic authority in the U.S. in the 1950's and 1960's, is quoted as saying that the entire basis for the existence of the kashrut organizations is the view of the Rashba. What did he mean by this?
There is a machloket rishonim and the Rashba holds that if a non-Jew, in the normal process of making a food product, adds some non-kosher element, even a very small percentage, then it is not batel. Bittul only works when it falls in by accident. This view is known by those who study Yoreh Deah since it is quoted in the Beit Yosef.
If you look at any of the standard Yoreh Deah books you will find, however, that the halakhah is not in accordance with this Rashba. Rather, any time the goy puts a small amount of treif into the food it is batel, even if it is intentional on his part. There is a famous Noda Biyehudah that discusses this at length. See Mahadura Tinyana, Yoreh Deah no. 56 where he permits a drink that was produced using treif meat in the production but the amount of meat was very small and could not be tasted. He states that it is permissible. There is a Rama who has a teshuvah and states similarly. (I am sure if you describe the Noda Biyehudah's case to people, even learned ones, and say that there is a contemporary rabbi who permits this, they will mockingly refer to him as a Conservative or Reform rabbi since in their mind no "real" rabbi who knows halakhah could ever permit something that has non-kosher meat in it!)
So now we can understand R. Henkin's comment. If you go to the kashrut organizations' websites and speak to them they will tell you that you need the hashgachah because sometimes the runs are not properly cleaned between kosher and non-kosher or milk and meat and some slight amounts of the objectionable ingredient might remain (yet here even Rashba will agree that it's not a problem!), or they tell you about release agents or that small amounts of ingredients are not listed on the label, etc. etc. The Rashba indeed holds that these last cases are problematic, but the halakhah is not in accordance with the Rashba. The hashgachot have raised the bar and are now operating at a chumra level here as well as in other areas. But the average person has no idea about any of this and has never even heard about the concept of bittul. Even if you explain the concept of bittul to him, his response will be: "OK maybe this is the strict halakhah, but I'm not starving so why should I eat something that we had to rely on bittul for. A person who cares about kashrut won't eat something that has even the smallest amount of treif." Since people haven't been educated about the halakhot, they assume that bittul is a kula to be used in emergency situations, and it is not their fault that they believe this, since this is the view that the kashrut organization hold and publicize.
There is a good article waiting to be written about how in the last thirty years we went from halakhah to chumra when it comes to food issues.