I feel I should point out that the items you've linked to are not being sold by Amazon but by third parties using Amazon's website. The same problems occur anywhere you allow Tom, Dick and Harry to sell things using your website.
Last year I bought some LED Christmas tree lights from E-bay. When they arrived I immediately was concerned about the mains cabling not being of sufficient quality so I cut off the moulded plug to inspect the cable cross section. That confirmed my suspicions - the cables were the cheapest possible things with the thinnest slither of metal surrounded by dodgy insulation that could break far too easily.
My attention then turned to the inline box with a CE stamp that was advertised as being a transformer. It was very light so, having already decided there was no way these things are getting used in my house, I started to cut open the box and it practically fell open without much effort. Inside discovered that there was in fact no transformer. Instead there was just a single 1/4w resistor in series with the mains, held in place with a blob of hot glue with incredibly bad soldering. If/when the glue melts the resistor would have been free to pull out of the hole exposing the unfused mains voltage to the outside.
The scary thing for me is that 99% of people will just plug these things in not realising the potential dangers.