Here is an example of the warranty on my canister filter:
"The mfg. offers a 3 year warranty from the date of purchase against defects in material or workmanship under normal aquarium usage and service.
We offer a 3 year warranty on all non-replaceable parts which means that the filter will be repaired or replaced at the manufacturer's discretion, free of charge, when the complete pump is returned with proof of purchase and postage paid. Please include $4 (U.S.) to cover shipping and handling.
This warranty does not apply to any filter that has been subjected to misuse, negligence, or tampering."
The warranty seems rather straightforward but for the average consumer it is a maze of legalese because the words in the warranty can have a different meaning in the law then they do in everyday conversation.
Warranties, IMO, are meant to be difficult to understand, offer minimal recourse to the consumer, especially for lower price products, and can be difficult for the consumer to prove that the mfg. is at fault for the failure of the product.
I agree with you that it can be more expensive to pack the item and ship it back then the item costs brand new. I will also hazard a guess that most people won't even bother. We are living in a throw away society. People want to pay the least amount of money they possibly can for a product because they need to stretch their dollars further.
But that is not to say that reputable manufacturer's are willing to lose the business of their customers by making inferior products, that would be a poor business choice. Sometimes it is the customer service that sucks and you just need to be a bit more vocal to get your shipping costs returned. Bad mouthing a company rarely gets anything positive accomplished so I'm not suggesting that route or inferring that the OP is or should be doing that.
I do believe that a company should stand behind their product and make the customer whole by either reimbursing their out of pocket expenses to repair/replace a defective item under warranty or offering them credit toward a similar product. I know this is done with recalled items and poor (bad) production runs of new products but it doesn't always happen fast. Just think of all the customers that don't know their defective item was recalled and they could have been entitled to a refund but have since avoided that manufacturer's products!! The squeaky wheel often does get the oil it needs.
"The mfg. offers a 3 year warranty from the date of purchase against defects in material or workmanship under normal aquarium usage and service.
We offer a 3 year warranty on all non-replaceable parts which means that the filter will be repaired or replaced at the manufacturer's discretion, free of charge, when the complete pump is returned with proof of purchase and postage paid. Please include $4 (U.S.) to cover shipping and handling.
This warranty does not apply to any filter that has been subjected to misuse, negligence, or tampering."
The warranty seems rather straightforward but for the average consumer it is a maze of legalese because the words in the warranty can have a different meaning in the law then they do in everyday conversation.

Warranties, IMO, are meant to be difficult to understand, offer minimal recourse to the consumer, especially for lower price products, and can be difficult for the consumer to prove that the mfg. is at fault for the failure of the product.
I agree with you that it can be more expensive to pack the item and ship it back then the item costs brand new. I will also hazard a guess that most people won't even bother. We are living in a throw away society. People want to pay the least amount of money they possibly can for a product because they need to stretch their dollars further.
But that is not to say that reputable manufacturer's are willing to lose the business of their customers by making inferior products, that would be a poor business choice. Sometimes it is the customer service that sucks and you just need to be a bit more vocal to get your shipping costs returned. Bad mouthing a company rarely gets anything positive accomplished so I'm not suggesting that route or inferring that the OP is or should be doing that.
I do believe that a company should stand behind their product and make the customer whole by either reimbursing their out of pocket expenses to repair/replace a defective item under warranty or offering them credit toward a similar product. I know this is done with recalled items and poor (bad) production runs of new products but it doesn't always happen fast. Just think of all the customers that don't know their defective item was recalled and they could have been entitled to a refund but have since avoided that manufacturer's products!! The squeaky wheel often does get the oil it needs.