My only issue with Amazon is if they send something and it doesn't get delivered. They don't have an easy option for that, just for returns. You can't return something you didn't receive. But you can work your way through it, it just takes time and effort.
When we bought our new townhouse a few years ago, DW started buying art to hang on the walls. I forget the company(ies) she was ordering from, but often (at least 1/3 of the time) the art would arrive with a blemish, or a lousy framing job, or something like that. Every single time they told us to keep the picture and they sent us a new one. So now we have duplicate pictures in the basement storage room. I haven't decided whether to try to fix the framing myself, or just give it to the church's White Elephant sale. But the markup on that stuff must be incredible, if they can just toss it away like that.
I don't think you bought the art from Amazon per se. You probably bought it through the Amazon Marketplace. With the # of items that are shipped out by Amazon facilities all over the world, it simply is not worth their time to pay for shipping an item back, entering it in a system, checking for flaws, and either returning it to the shelf or the mfg/seller.