Refund Paradise, America

I have been in American for three month. One of the things that I like and want my country also to follow US is a well settled refund policy.
While I stay in here, I have bought many items from various kinds of place from big market to small one. For me there have been two times that I had to get refund since I came to America. One is for a belt that I had bought at the Macy and the other one is for a facial cleansing form that I got it at the Target. The reason that I had to get a refund in first case is that After I bought a belt, I realized that was too long for me so I could helped to asked for refund. And second case is that because of negligence of word, 'acne' printed in the front of facial form. My condition of skin is not an acne if I use that product, it is expected to cause facial irritation I realized after I read warning printed in back of that product. Actually, all this case happened due to my careless and mistake, I could not anticipate that I could get a refund. Surprisingly, When I went to Macy and Target to get a refund, I could get refund easily;I just showed them my receipt and then they gave me refund even they didn't gaze the condition of the products carefully. I was really surprised after I got refund much easier than I expected. And I was surprised one more time after I heard the story that one of my friends got refund for a sunglasses after she used it for about two month. In her case, she went to Macy get her sunglasses repaired but they could not repaired so my friend asked them refund, in then end, she got 100% refund even though she used it for a while.
I am not sure all the markets are guarantee to give refund within 100 days however, big market like Macy, Target are guaranteed it. In my country, when I get refund it, I have to ask for it within a week from the day of purchase and clerks would gaze my products if I damaged it or not. In my opinion, my country's allowed day of refund is too short and on the other hand, in the US's case, it is to long.
I really wonder if there are people who abuse this system.