Warranty and service experiences

Sure. To cite one example, Amazon is an Apple Authorized reseller. If you were to purchase a new Mac directly from Amazon and it doesn't work you have 30 days to return it for a full refund. If you were to purchase a new Mac directly from Apple you only have 14 days to return it for a full refund.

As ku4hx wrote you have to read and understand each seller's policies. At first glance Amazon's policies may appear to be more generous than Apple's, but there are a lot of caveats associated with them. For example, if you purchase a Mac from Amazon and it doesn't work you have 30 days to return it, but Apple's 14 day return policy is a "no questions asked" one. You can return a Mac to Amazon for a refund only if it doesn't work or if you didn't open the box.

And, unless the Mac specifically "Ships from Amazon" and "Sold by Amazon"... then it isn't, and you have to read the particular vendor's return policies, which probably won't be as generous. Amazon makes that clear.

And by the way... if Amazon indicates the Mac is "renewed" then it is not new. This is a common sales tactic to obscure the fact the Mac is used. Used ≠ New. To my knowledge all of them are Amazon Marketplace items which is only slightly better than purchasing something from Facebook Marketplace which might as well be some stranger on a streetcorner.

This is only one example. The point is that you need to avail yourself of each individual vendor's sales policies.

Given all these facts it boggles my mind why anyone would purchase a Mac from anyone other than Apple.

My experience with Apple's service after the sale is it's top tier in every respect.

As to resellers, my only experience is with Amazon and they too live up to their policies.

BUT, you have to read and understand each seller's policies. Don't assume all are the same. Due diligence and caveat emptor both apply.