Suppose I am a television manufacturer. I produce TVs that can (and do) show High-Definition broadcasts as well as standard definition broadcasts.
For marketing purposes, I clearly state that all my TVs can show HD broadcasts - my question is: Is it legal for me to charge a additional premium for HD viewing, even though the entire functionality already exists in a non-premium version? Any smart person reading the literature would realise that the TV already supports HD, but a less-smart person - let's say they're ripe for the picking.
Or alternatively, is there any stupid-person-protection-laws that prevents me from selling identical items at two different prices by advertising specific features, even though from the business point of view, the premium is pure profit?