It's a fine supposition, but these suppositions often get passed around as if they're true and self evident. The reality is you don't have distinct information

It's a fine supposition, but these suppositions often get passed around as if they're true and self evident. The reality is you don't have distinct information about what the government is collecting. Instead, what you have is information about what's probably possible. From that standpoint it makes sense to err on the side of caution, and assume it's all being collected. But, while this is an effective risk calculus, it's different from having access to the ground truth.