I don't think corporations are stupid at all, they're the collected intelligence of thousands of people being used with the moral and ethical consequences abstracted away to where they can act in horrifying ways and not feel any remorse. This is why probably the hundred or so people involved in denying a cancer patient's claim for insurance payment don't feel bad; none of them made the decision, it's just a process.
So, with that in mind, I don't think Hanlon applies here, if you want a razor, use Occam's. And the theory here that requires the least assumptions is that corporations would sell their own mother if it made them one red cent, so when I hear "priceline changed it from $129 to $149" my prevailing assumption is the low price was to get you in the door, and they've found that a price increase of $20 at the point of sale isn't enough to deter customers. They're probably A/B testing a number of increases to see just how much they can squeeze from people.