"But at the end of the day, any company that has your name/address/credit card number because you bought something from them is going to know. A lot. It's unlikely that any data inside said company isn't going to be de facto visible to them for whatever purposes that company so desires."

Hate to single out any one comment, but this "point" gets made quite often on HN. Unfortunately there is always something missing from the ensuing discussion. The customer did not buy anything from a "tech" company. Yet the people who think the "tech" company intermediary is a legit business model want us to believe they have the same right to name/address/credit card number. That does not make any sense.

If a merchant where a customer bought a product has her personal information, let us assume that is acceptable. (Without "tech" companies, only 20 years ago, this was never a major prvacy concern.) A merchant could transfer the information to another party, although she may allow the customer to decide whether that is permitted.

If merchant A does transfer the information to merchant B, its is likely that merchant B believes it shares customers with merchant A, i.e., customers of merchant A are likely to be interested in products from merchant B. We could argue that this is a major privacy concern, however besides the "junk mail" aspect of it, we should be able to agree that relatively few consumers were ever bothered by this sharing.

If the merchant transfers personal information against the wishes of the customer and this annoys the customer, then the merchant could risk losing the customer's future business. IOW, there were and still are some explicit and/or implicit limits on whether and where a merchant will transfer personal information about its customers.

However, the "tech" company intermediary is different from a merchant and is subject to no such limits. The customer has not purchased any product from the "tech" company. The "tech" company's customer is not the person purchasing a product from a merchant, it is the merchant, the merchant's competitors, any other merchant on planet Earth, anyone who is interested in influencing a computer user.

The data collection by the "tech" company intermediary is a new privacy problem. It is not the same age-old problem as merchants sharing customer lists. This is a new, additional privacy issue, with far more invasive potential. The structure, size and scope of the problem is entirely different.

Suffice it to say, there does not seem to be any logical connection between the age-old fact that a customer's personal information may be held by a merchant and the common HN comment thread suggestion that this somehow obviates any issue a customer might take to have her personal information held by a "tech" company. The later is a novel privacy threat with much greater invasive potential. Certainly, the fact that no one today has "perfect" privacy (they never did) is not a justification for sweeping, unbounded personal data collection by "tech" companies.

A merchant needs certain personal information to complete a transaction and deliver a product to a customer. The "tech" company wants the personal information to sell ads or take a percentage of sales based on use of its computers. These are very different scenarios and do not amount to equivalent problems.

The truism that no one can ever have "perfect" privacy does not logically support a conclusion that therefore unlimited "tech" company data collection is acceptable. It feels very much like people who have bet their career on the continued legality and effectiveness of the "tech" company business model want privacy-conscious commenters and readers to just "give up". Credit card users cannot have "perfect" privacy therefore they should be content with no privacy at all on the internet (the type of world where where "tech" companies can stay alive). That does not make sense.