Can Dells trade in program on laptops & desktops really be trusted?

Dell UK expects it's trade in customers to gamble their old products on their new.

As with any trade in program, it allows previous customers of any purchased products to trade in their old products and get a discount on any new products they have. It's a great concept for anyone who wants to keep up with the latest changes in technology. So what's wrong with that? Well nothing really.

Where Dell UK goes wrong is that they expect their customers to make a purchase of one of their new products before they give their customers any hint of a quote on the product that the customer is returning, thus expecting them to make a gamble on the value difference. and?

Well, once Dell has a purchase from one their customers, they then have the power to put just about any price on the return product they receive granting them the power to possibly exploit their customers and short change them. Their customer already having placed the deal would have no choice but to accept what ever quote was given, whether they agree about it's value or not.

Now if they had a trusted policy like most trade in programs where they're able to give you an estimated quote first hand, not only does this give customers the opportunity to weigh up whether it'd be worthwhile or not beforehand and thus removing the gambling aspect of it, but it'd also removes any power to exploit customers and short change them, unless they want to risk being branded as liars by going against their original quote estimate.

So this begs the question. Why don't they?