When you purchase an item of consumer electronics it isn't actually the manufacturer who has the main legal responsibility if the product goes wrong. The oft quoted "sale of goods act" applies to the person with whom the customer has exchanged the ownership. In most cases the contract of purchase is with the retailer and thus the onus is with them to assist the customer after sale. A manufacturer has a limited responsibility in the case that the retailer cannot, or will not, honour the warranty but in most cases it is the retailers generosity and discretion that prevails when the customer is speaking directly to the manufacturer. Also remember that after six months the customer is deemed to have accepted that the goods are in working/acceptable order and if there is a problem after this period the customer must prove that the product was faulty at manufacture. Under six months the manufacturer must prove the product was not faulty at manufacture.
A manufacturer warranty is actually a form of insurance that is generally taken by the manufacturer on the products (either internally or externally guaranteed) and it is measured against the expected returns (when producing hundreds of thousands of units some must fail). A manufacturer may provide the company that purchases (the retailer) that warranty at whatever level suits their business model. In some cases a warranty is a point of negotiation because it must be built into the cost of dealing with that customer. In some circumstances a sales package may be offered to the retailer that says they cannot return any product to the manufacturer, in which case the retailer gets a better price because the cost dealing with that retailer is lower (in both logistics and support). A retailer will have a common warranty period that they can pass on but sometimes they might agree a shorter period because either the quality of the goods cannot be so easily quantified (re-manufactured product) or because they can achieve a lower retail pricing but give the customer a lower service level.
In most cases where a retailer sells the same product (not re-manufactured) as another but offers a lesser warranty this isn't an indication that you are getting a lesser product and it isn't that the retailer is trying to con the customer. It is just that they are offering a different service one that is consummate with their business model. This is also the case for extended warranties: they are offered where the supplier wishes to give the customer greater choice or an enhanced service. Although I will acknowledge that in some circumstances extended warranties have been pushed on customers to increase margins and also that re-manufactured stock (which often has a lesser warranty) has sometimes been sold by retailers as new stock without the customer knowing.