I suspect it's more a question of scale than anything else.
Yes, advertising is always right on the edge of falsehood, but that's just an image. You suspend your belief until you actually experience the product.
If you were a food critic, you'd expect the restaurant to take extra effort to make sure that your meal had nothing abnormal about it, but you wouldn't expect them to add extra stuff that's not in everyone else's meal.
I think cars are the same way. There's a good reason for press cars. They're (supposedly) examples of how the car should be in it's best form. They've made sure that it's in good condition, which you can't necessarily say for the average public model.
There's a bit of a step from giving someone a perfect example of a stock Ferrari, and giving them a tuned version masquerading as stock. If a standard model has 550bhp and the press version has 580, that's not right.
And if other companies do that too, they should get just as much stick. Just because everyone else goes around kicking people in the nuts, doesn't make it right. I wouldn't be surprised if similar stuff is common amongst all the performance car brands, but it's still BS.