While I can see why some people think that this is an invasion of privacy, I do not think that it is. I would say that the things we buy would become a matter of public record just about wherever we bought them. I do not see where we have much of an expectation of privacy in the things we buy.
Think about how things were in the old days when people bought things from “mom and pop” stores in their towns and neighborhoods. The proprietors of these stores knew what their regular customers bought. They might have suggested things that customers might try based on that knowledge. Or think about how things are if you are a regular at a given restaurant. Workers know what you tend to buy and might suggest new things for you to try based on what they know that you like. When this sort of thing happens, we think that it is great because we are getting personalized service from people who really know us.
While I realize that Amazon, Netflix, and others have a much greater ability to “remember” everything we buy or watch, I do not think there is a moral difference between what they do and what I discussed in the previous paragraph. In a sense, you can even argue that there is less invasion of privacy because Amazon and Netflix are using impersonal algorithms to remember what we like and predict what we might like. This is better than having some store owner knowing everything about what you buy and perhaps talking to people about it. I would also point out that Amazon, at least, allows you to delete items from your history so that you do not get recommendations based on those items. This increases our ability to maintain privacy.
Overall, I am not worried about Amazon, Netflix, or others invading my privacy. I feel that the purchases I make are, in essence, a matter of public record. I think that the suggestions these businesses give are valuable to me and their value is enough to overcome any reservations I might have about potential invasions of privacy.