“A deleted App is deleted. It does not remain on your iPhone. “
You have no way to know what software is behind the software.
If folks want privacy they need to get a dog.
In many ways we do. The underlying software of Apple devices is UNIX, open source and available to see. Apple is the only mobile device which offers as its business model privacy as a selling point. Google on the other hand offers Android with a business model of just the opposite.