The example given by Adobe isn't just poor for the reason Warm Braw gives. Why would a company give a product away for free that the customer has just expressed an interest in buying? They wouldn't.
In reality, with enough data, Shell would know to mark up this guy's petrol, given he's the kind of weirdo who shops for petrol by brand rather than price or location. And then when he goes to get his car washed they will urinate on him. And it.