It’s interesting that only GET calls are metered. Is this a common thing to do?
I wonder if this is also being done to limit marketplace data being scraped with the API or limit how this data gets used by limiting low margin business models. Increasing the fees will have these effects.
I've been noticing this happen more lately. Intuit QuickBooks did this exact same thing for GET calls this year as well.
My theory is they see POST/PUT calls as adding value and are actions that customer need to perform and help the platform (adding products, inventory, etc). But GET calls they see as leaching off them and not core requirements.
The huge gap in this theory are things like Seller Fulfilled orders which you have to GET, but for Amazon they have always pushed hard for Amazon Fulfilled instead.
In the end I think this is all mostly to keep things/control in-house as much as possible. Some apps will shut down, others will pass the cost along the sellers. Sellers always lose.