The same way you know that they aren't sending special agents to harvest your DNA from your Starbucks cup and analyze it without you giving them any permission

The same way you know that they aren't sending special agents to harvest your DNA from your Starbucks cup and analyze it without you giving them any permission in the first place, or that your bank actually has your money, or that the government actually exists: you don't, but you have to engage with the world at a baseline level of assumption of good faith when not proven otherwise, or you'll lose your mind, and it's generally worth noting which corporations acknowledge potential abuse cases, specifically and affirmatively commit to not doing them, and have a plausible monetization and profit scheme without any hidden abuse.