I don’t think Amazon “thinks” they know more about your business than you do. They don’t have to. This is not about whats good for your business, but what’s good for theirs. Your overhead means nothing to them - you are free to sell on your own website or other marketplaces. Amazon attracts customers by keeping prices as low as possible for most items.
Amazon doesn’t care what your costs are. They care what the customer is asked to pay because a happy customer comes back.
Amazon doesn’t care how long your carrier takes - the work with all the carriers and let them dictate what they can do. Faster service means happier customers.
Amazon doesn’t care if a return is for reasonable or unreasonable means - they make money either way - but the customer that feels safe in making a purchase is going to come back more often than not. That means more money for Amazon.
Amazon doesn’t care what natural or manmade disasters might affect you, and it’s pointless to even try. They don’t know (or care) if your package has to be re-routed around a wildfire, or a flood, or if the carrier can even do that. They care that the customer gets what the customer pays for.
Amazon knows their own business - keeping customers coming back. That’s what they are “selling” you - a loyal customer base. Your business model doesn’t mean anything to them. They set their rules and you can either try and keep up, or get out of the way of the next person.
I don’t think it’s in our best interests at all, and I don’t assume it will ever be. They have the data and metrics to show what they are doing works. It’s my job to run my Amazon business in a way that can still make me money while complying with one of the most lenient return policies available.