Amazon has built a giant business on top of open source technologies. Don't you think it is natural for the open source community to expect that Amazon give something back to them out of courtesy?

The GP asked for a good thing that came out of Walmart Labs hinting at the idea that good things come out from Amazon but not Walmart Labs. Then a few commenters pointed out a few links showing the good things that came out of Walmart Labs. All of these good things happen to be open source. So it is quite natural to ask what good things Amazon bothered to open source after having built a billion dollar business on top of open source.