I've now opted for the "free" shipping that you get when you spend $25+. Items that I cannot wait for I will buy local, which usually now offer same day delivery.
That doesn't sound entirely artificial to me, though? It seems more likely that they're reserving stock in closer (and likely, more expensive) warehouses for people who are paying for two day shipping, either by having a Prime membership or by paying for the shipping.
While there are definitely periods where I would have agreed with you, recently Amazon has seriously increased the % of products which are deliverable same day.
It's also not just for common items. I can buy a thermocouple amplifier board and have it delivered today. It really scratches an itch when you can get components for a project delivered THAT DAY. I could be playing with thermocouples TODAY. Hard to resist.