Dovnyc,
“business risk” is not a halachicly sufficient barrior to ensure the reliability of the kashrus.
Yes it is. See R’ma Y.D. 114-5
halacha demands that even if a non-Jew simply DELIVERS meat or wine (that was fully prepared by Jews) it must be double-sealed
That din does not apply to baked goods.
My previous comments were not meant from a strictly halachic perspective, I was just pointing out why someone might be more comfortable buying from a store with a hechsher, or buying sealed items.
On a side note, why does your posting style seem so familiar?