Maybe not by default, but if they asked the users and explained what is this used for, it is likely users would say yes to the use case you described as it objectively improves their user experience when using Amazon (granted, ads/recommendations would need to be meaningful and designed in a way to actually improve the experience of the average user with a way to completely turn them off for a user who doesn't want it).

Problem is when a company use data that the user did not explicitly opt-into sharing with them, to then diminish their user experience of consuming the web by for example stuffing tons of targeted ads on every major site on the web, leading to barely usable sites and intelligence insulting outcomes.