Hello,
My view on processes where Zero rework is impractical or Undesirable would apply mainly to manufacturing process,
where the cost of "Rework" is higher than manufacturing a "New" product - For example a small component of an electronic device like LED bulb or such similar products where a dismantling to fix it is costlier than reworking to fix it ( I am not a industry expert however, this is an apt example I could think of)
FMCG manufacturing of products especially with foods, daily consumables where the variation in the look and feel of products is not critical in comparison to the desired purpose of the product. In such situation it is not desirable to "Rework" to ensure "uniformity" of the product.
Based on cost/benefit analysis, TAT for rework are the key metrics that needs to be studied to arrive at a conclusion on impracticality or undesirableness of rework should be taken.