>Amazon is the only place I have seen blatant user-targeted dark patterns. "Order within the next hour to ship today". Four hours later: "order within the next 2 hours to ship today".

That could be a reaction to facts on the ground. To give you a guaranteed shipping window, they need to estimate sales. If sales come up lower than expected, the cutoff moves a few hours.

You see this kind of thing all the time in airline seat pricing.