You saw a mild steel can being made and assumed however it was made applied to all similar objects no matter what they are made from, then you have assumed that an object which is not of the same design can be easily made by some similar method with any material, sorry but that's to much assumption.
Also you have used bleach in a stainless mug and because you have not noticed any corrosion have assumed there is none, once again an assumption too far. It is a fact that all stainless steels corrode when exposed to bleach, some more than others, but if the exposure is limited there will be limited corrosion to the point where it might be minuscule.
It is a fact that certain stainless steels are more suited to certain processes or uses, I don't know for certain what stainless some manufactures might use for sinks, and why they are used, but I wouldn't be calling them 'poor quality stainless', without knowing the facts.