Because of AWS scale it cannot be the cheapest. Amazon cannot use odd lots or small lots, which means that it has very few possible suppliers and those suppliers will never be the cheapest.
Same goes for the network infrastructure. While it is possible buy 100Gbit/sec at a throw away price to because some sales person needs to make his numbers and neither he nor his director of sales thinks Kmod Hosting would be able to fill the pipe it is buying, Amazon would need 900Gbit/sec for their exit and no one at the vendor is going to blink at making Amazon pay higher price than Kmod Hosting.
1 month of sales hunting has got me a PC rig for literally 2/3rd of the cost of buying without waiting. And this was an optimised build in the first place.
Because of AWS scale it cannot be the cheapest. Amazon cannot use odd lots or small lots, which means that it has very few possible suppliers and those suppliers will never be the cheapest.
Same goes for the network infrastructure. While it is possible buy 100Gbit/sec at a throw away price to because some sales person needs to make his numbers and neither he nor his director of sales thinks Kmod Hosting would be able to fill the pipe it is buying, Amazon would need 900Gbit/sec for their exit and no one at the vendor is going to blink at making Amazon pay higher price than Kmod Hosting.