The whole idea of having a return policy is to give any customer a chance to use the machine before being completely out several thousand dollars. That is also why they have a restocking fee... So if you try their product out and don't like it or don't want it, you can return it for a fraction of the cost.
No - just 10-15 years ago, there was no such thing as a 'restocking fee'. Stores assumed that customers only returned something if it was defective, or something else came up. For example, you just lost your job, now could not afford something you 'just' bought. Stores were very liberal in allowing returns. In most cases, a receipt was not even required.
What happened was that people like 'murdercitydevil' abused the system and used it for 'free rentals', so stores have now added restocking fees to discourage this. I remember for my high school prom, that some girls did the unethical and bought a dress before the prom only to return it right after the prom. This was cheating back in my day, but the businesses didn't catch on until it became more widespread. And this started about 10-15 years ago.
People like 'murdercitydevil' have caused this restocking fee with their unethical practices. What he did is not illegal, but definately unethical. Is it illegal to sleep with your boss to get a promotion? No. But is it unethical? Yes.