That's why some industries have separate "verification" and validation" (V&V) activities. Verification is checking against formal or at least known requirement

That's why some industries have separate "verification" and validation" (V&V) activities. Verification is checking against formal or at least known requirements like those being discussed in this thread. Validation is a set of processes for ensuring the specifications actually correspond to how the product ought to work. "How it ought to work" is open-ended and meant to include real-world aspects you didn't know beforehand. For example business logic assumptions. But despite being open-ended it is possible to formalise and track the process of looking for issues systematically. In your example of YouTube showing Polish content when you travel, verification is the process of checking the website uses the IP correctly because using the IP is specified somewhere, but validation is the process of asking "what's the right thing to do when a user travels, is it really to use the IP?" and "let's systematically research what issues are affecting users due to incorrect specifications that we should change".