Attributing emissions to Amazon/AWS is not a trivial problem. What you'd really want to estimate is AmazonEmissions-CounterfactualEmissions, which is the emissions caused by companies that would jointly provide the services demanded by consumers from Amazon, in the counterfactual world where Amazon didn't exist.
If Amazon reported their emissions, we can corroborate their Scope 1 emissions with other companies' Scope 3 emissions and get an indication of just how much Amazon is directly responsible for.
Amazon, however, discloses nothing. This is the kind of thing that regulations are for. In other countries, disclosure is mandatory, and I would say for our survival as a species, absolutely essential. We need data before we can know what direction to take.
When we do our GHG assessment at the company where I work, we estimate our Scope 3 emissions based on what has been leaked about the location of Amazon's data centres and what we know about the electricity grid in those locations. We look at our CPU usage on the AWS console and estimate the energy required with some assumptions of the hardware.
It introduces a lot of uncertainty and we could do better if Amazon disclosed their emissions.
