"ingredient" kosher vs hechsher

Question

A question asked in total earnestness: On the audio file of Rabbi Abadi on this site someone asks about whether you can rely on ingredient listings in the US to determine whether something is kosher. The sound is a little hard to make out but it sounds like he says yes provided you know what the ingredients mean. But it is hard to make out the voices and I know I am not getting it all down. I have this book on keeping kosher published by a major Jewish school. Based on this book it would suggest that (a) we don't know the kosher status of the production equipment on which they cooked the food even if it was washed down before the run and (b) they list 27.5 reasons for each common processed food ingredient as to why it could be a problem (e.g. stearates, "natural flavors" etc). So basically they might as well just say you can't rely on ingredient lists. An example would be a commerically produced vegetarian egg roll from a company that also produces a version with pork in it. On the vegetarian egg roll package everything appears ok. Just for my own understanding, is it fair to say that whoever wrote the kosher guide I cited was being unnecessarily strict --and if so can you help me understand why (I have little textual knowledge of my own to go on--though I also have an Artscoll "kashrus" book which requires way too much prior knowledge to be able to understand!). I do also agree that hashgacha has become a business in this country! Thanks in advance for your help!