alt Hacker News> The best solution is a constitutional amendment that actually enshrines a right to privacy.
This seems like a category error on two fronts. First, the constitution is a law which applies to the government, not to private entities such as stores. The proper way to restrain behavior of private entities is with a regular law. Second, we already have a right to privacy under the US constitution (amendment 9 says that rights not enumerated in the constitution are still valid rights, and amendment 10 says that they are reserved to the people).
Moreover, as others have said, you really don't want to use the constitution as your method of first resort when solving societal problems. It's hard to change (by design), and you don't want to have unintended consequences baked in at that level. Sometimes an amendment is necessary, but that needs to be used very sparingly.
The constitution applies to government, yes. But it's predicated on an enumeration of inalienable human rights that need to be recognized and defended. That's what makes our government different from other instances of government. The enumeration of rights sets the stage for what we value as a society. And privacy is sorely missing from the modern dialog.
I'm sympathetic to the idea that the right to privacy in the digital age is fundamental enough that it needs to be distinguished in our founding documents and elevated to a level on par with the freedom of expression in more than just case law. Most importantly, the government shouldn't be able to spy on citizens either. Right now it does. This has implications for encryption law too.
The point of an amendment is to establish the axioms upon which we evaluate all future laws. From there we can build a legal framework that applies similar ideas to the private sector, as and where appropriate.