BTW, the fact that the national hechsherim are lenient does not surprise me (in fact, before engaging in this discussion, I asked a posek how we pasken l’maaseh, and he told me that the poskim he knows are machmir l’chatchilah, but that the hecsherim are meikil). There is definitely what to rely upon, and their goal is to provide kosher food to as wide a public as possible.
I was not debating this issue from the perspective of a hechsher, rather from the perspective of an individual who wants to follow basic Halacha, without being unduly machmir, nor relying on kulos.
Along the way, it’s interesting to discuss the shittos of individual poskim.