I don't think your claim about Amazon is true. But even if it is, it's not relevant. None of the OSI licenses require improvements to be contributed back to the original project. The most restrictive of them simply requires improvements to be open to the user.
The intention of open source licenses was never to force those who redistribute the software to improve on it. It was to provide end users with the freedom to be able to do that themselves, by distributing the improvements as well.
It's unfortunate that licenses from a generation ago don't adequately cover all the nuance of cloud computing. But the reality is that open source licenses were never about preventing companies from profiting at the expense of original developers. They were about user freedom. If you're unhappy with the way a company is using the software you open sourced, that is a sign you weren't prepared to commit to what open source means, philosophically.
Something like the AGPL would be preferable, if also more controversial. Then you'd also have a peanut gallery of people telling you your software is "source available" instead of open source.
Perhaps that was the intentions of the license creators, but famously Linus for example chose the GPL license precisely as a quid pro quo - I give you code for free, you give me back code for free.
We have not seen such an egregious abuse of open source software with any other company. Most companies that make use of a large amount of opensource actually contribute a fair amount back.
Like hiring on the core developers or making a large amount of code fixes and feature development contributions.
Amazon does neither of these things.
Take a look at any highly successful society or community. There is a large amount of gifting and selfless behavior