I noticed this at the grocery stores. They introduced odd fractions. One week something would 5 for $4 or 3 for $3.50 etc. Also they put the sale signs in black letters on red cardboard so they were very hard to read. And of course they placed expensive things at eye level and cheaper things less accessibly.
Just about every price label (near me, at least, in all grocery stores) will also include a price-per-quantity. Easy comparison, as long as one isn't measuring containers while another measures ounces.
The problem is that some grocery stores (or products, it could be either) use different quantities. For example, one product might be price per quart and another is price per gallon. I've even seen volume and weight being used for similar products.
I frequently shop by looking at the price per amount comparisons and it drives me crazy when you're looking at two different toothpastes and can't make an effective comparison.
It is my understanding that this meets the legal requirement, but also satisfies the business desire to confuse the customers trying to make a decision based on the greatest value for money.
