Now this is timely....
First, the long digression into why it's timely....
<digression class="rant pissed sears-sucks">
I have a project - blew the gearbox on the snowblower and want to have it repaired before the storm comes in on Feb 2. So, on Jan 28, I go to Sears Parts Direct and several other places. Sears is more expensive, but they offer expedited delivery to have it here on Jan 31. Sold! I also ordered some semi-special grease for snowblower gearboxes and some gasket maker via Amazon, plain old Prime, which also said Jan 31 delivery.
Yesterday I get notification from Amazon - order shipped, expect it on Jan 31.
Then I get notification from Sears - order shipped, expect it Feb 3, which is the date they were going to get it to me without expedited shipping. Shipping method: UPS Ground from Minnesota to California.
I call them up and say, "You promised delivery by Jan 31."
Answer: "Well, you ordered on a weekend."
Me: "Right, but you said Jan 31"
Her: "Do you know anyone who ships on the weekend?"
Me: "That's not the point. The point is you promised Jan 31 and you're delivering Feb 3."
Her (like I'm stupid): "Yes, because of the weekend. You should have known that it wouldn't arrive on Jan 31 if you order on the weekend."
Me: "Well why did your website promise Jan 31?"
Her: "Because expedited shipping typically takes three business days and the website doesn't take account of weekends."
WTF????
</digression>
So, back to your point. This has become completely unacceptable to me. Not just Amazon's fast delivery, but their accurate estimates are key to letting me plan and it affects how much "stock" I keep on the shelves at home and at what point I decide to drive into town and fetch it myself and when I trust the UPS driver to deliver my Amazon swag.
One article I read pointed out that the end point of this is to own a lot less stuff. If I have a project every couple years that demands a chop saw, should I own one? I own one now, but if I could rent one at $50 per time and delivery was fast, on-time and cheap, why would I own one?
The author was asserting that Uber and Zipcar, for example, is just the leading edge. As delivery gets faster and faster and cheaper and cheaper, your own/rent threshold gets pushed lower and lower.
