The majority of shoppers do not actively price shop. If they do at all, they do so passively in the form of selecting a retailer based on perceived prices (i.e. they may not compare pricing between Target and Walmart on specific items, but they may choose to go to Walmart due to the perception of Target being more expensive).
At this point, Amazon is riding on the momentum created from their previous habituation. They built up a (true) reputation for being incredibly cost competitive for the products they carried, and enabled minimally delayed gratification in the form of 2, 1, and same day shipping. Because of this, they became the retailer of first choice and people only went elsewhere if Amazon didn't have the product they wanted.
Then they widened their inventory to items that weren't as capable of being efficiently shipped in individual units with last mile residential delivery. They also shifted more and more to holding less inventory on their own books and having third party sellers fill that void. And then had to start collecting taxes nationwide so they could more easily build out their distribution network without tax-related geographic constraints. All of which led to more and more price inflation.
But Wikipedia says it best[1]:
"New behaviours can become automatic through the process of habit formation. Old habits are hard to break and new habits are hard to form because the behavioural patterns which humans repeat become imprinted in neural pathways,[7] but it is possible to form new habits through repetition."
As long as consumers default to Amazon, they'll never notice how uncompetitive some of their product pricing has become. And as long as Amazon's inventory keeps expanding and they get closer and closer to instant gratification from compressed delivery timelines, consumers will have little reason to look beyond Amazon and change their habits.
[1] https://en.wikipedia.org/wiki/Habit