The funny thing is, the shipping is all done through the same channels and I guess there's not really a way to slow it down selectively, so the way they do it is sit on free-shipping orders for a few days before shipping. They used to always ship same day or next day, now several days go by at the least before the shipping starts.
Are you sure you're ordering from Amazon, and not some two-bit vendor that isn't Prime eligible?
You're either totally making this up, or it's due to differences in how your nearest Amazon warehouse is handling things.
I just checked every single one of my orders in the past 6 months, and they all shipped same day, arrived exactly 2 business days after ordering. There was one order that took 3 days to arrive (shipped next day instead of same day), but it was two items sold by third parties.
In fact, I ordered something (computer case) TODAY (2/5) and it has already shipped and is scheduled to arrive on Fri. (2/7)!
Do you even order, bro?
The respondent was referring to Super Saver Shipping, which is still free for many orders of $25 or more. Before Prime existed, Super Saver shipments usually shipped the next day, and if you were fortunate enough to have a warehouse nearby, you'd effectively get next-day or 2-day shipping without paying for it. But after the introduction of Prime, Amazon had to incent customers in such a position (of which there are many) to pay for it, so they artificially delayed Super Saver shipments by several days so that they could never arrive before or at the same time Prime shipments would.
As I mentioned, I was talking about the free shipping, not the Prime shipping, which is $79/year.