I've gotten Sunday deliveries even with the free 2 day delivery. I think it must depend on your location.
Saw a USPS delivery guy on Sunday in Philadelphia; asked him what's up with that and he said USPS delivers Amazon packages on Sundays. Sure enough he had stacks of them.
I work 90+ hours Mon-Friday. Weekends are my time so not having to wait all the way to the next weekend is great.
What line of work are you in?
Just ordered something with regular Prime, and the checkout page indicates item will arrive on Sunday. First time I've seen this.
Still not as good a deal as free delivery. I don't get you impatient people. I am perfectly fine waiting a few extra days.