Anecdotal, but lately, I've noticed that items I purchase do not ship immediately from Amazon, so while the shipping time itself may be 2 days, I get the product several days later which kinda defeats the purpose of Prime.
Not to mention that several of the items that I purchase are 'add-on' items, which means that I need to accumulate $25 worth of items to ship them (which is pretty much what every non-prime member does too)
I have a friend who works as an area manager in one of the bigger fulfillment centers and he offered a good reason for the processing slowdown after Christmas (although it doesn't explain how the issue is still alive).
Staffing a warehouse requires a lot of foresight. Overhead has to be kept lean and demand is very seasonal. Amazon forecasted their largest holiday season ever and staffed accordingly but the information they used to forecast the post-holiday slowdown assumed trends would be roughly similar to previous years. It turns out that this holiday season was a sort of tipping point for consumers acceptance of online purchasing and post-holiday demand barely dropped. All that seasonal labor had been let go but they needed to bring on a large number of permanent employees which takes time.
I don't think it takes ~3 months to find the necessary workforce but I think it explains some of the issues Amazon has been experiencing lately.
Ah ha! I was wondering why one item I ordered Prime 2 day was shipped 1 day UPS. A warehouse bottleneck would explain it.
As for permanently bulking up, I can think of at least several factors:
First Amazon has to realize there's been a permanent change in behavior, vs. e.g. more people doing late holiday shopping.
Then they have to figure out how to address this.
And there are no doubt classes of temp employees who wouldn't be interested in permanent jobs; I'm particularly thinking of the ones who travel around in RVs and stop by an Amazon warehouse for the Christmas season for that sort of work. Many if not most are probably gone by now.
If you are a prime customer, you get a delivery date promised to you when you add the item to your cart, and it is confirmed when you check out. If Amazon takes longer to ship, they upgrade your shipping to Next Day so that it will arrive on time. And if they miss the promised delivery, you can call up their customer support. I don't know if it is official policy, but I've heard people claim that they got a month of free prime membership.
Also anecdotal, but I've noticed that when I pay for shipping, the time it takes for items to leave the warehouse appears to be less compared to selecting "free" super saver for order totals > $X.
Not to mention that several of the items that I purchase are 'add-on' items, which means that I need to accumulate $25 worth of items to ship them (which is pretty much what every non-prime member does too)