Amazon may be monopolistic, but I have access to more products through from different brand names than I do through the rest of the local multinational chains. I see your point, but it’s also pretty hard to address without favoring other potential mega-corporations nowadays. The core problem is that there is one country that can realistic regulate it, and it is profit driven. Individually, each country can try to compete by subsidizing the competition in the areas those companies succeed in, by say putting decent refund and customer care into the law, subsidizing insurance to that extent, and making distribution networks accessible to small business. Once those standards are in place, it becomes easier to prosecute Amazon for anti-competitive monopolistic practices if they don’t stick to them. The problem is, each country usually has their own interests that don’t care for that either, and it wouldn’t be international.
Amazon should be divided into different businesses, but if US telecoms have proved anything, it’s that they usually end up working themselves back into the same group. But I see that as a separate more overarching issue than the rights of the workers it employs and the quality of their employment in their distribution warehouses.