I am deeply disturbed by this thread. I agree whole heartedly with the OP.
While I am not in the kashrus business, I do have semicha and keep myself informed regarding kashrus issues.
One only needs to read the monthly magazine Kashrus to be aware of some of the many reasons one needs to rely on hashgacho and not just checking ingredients..
[1] not all ingredients need be listed
[2]
[3]
[4]
[5] same as 4, but for any other listed ingredient
[6] every person working in the plant is trusted that nothing else gets placed in the product?
[7]
[8] who knows what this plant produced in the same equipment before this product was made?