Is there any reason to assume they are “so focused” on it? Keeping an eye on unit or per-weight prices is somewhat conventional and pretty easy—at least I think most major grocery chains around here include that info right on the sticker.
At least where I'm at they're legally required to include that info and they appear to comply maliciously whenever possible. Sometimes it's slightly wrong. Often the unit of weight changes between items of the same sort. It's absurd.
