Yes, virtually every commercial application I've ever seen allows exfiltration of data, usually close to all of it, and you agree to it by signing both an EULA and privacy policy.

Based off of that, I then assume that other companies are exfiltrating as much data as possible off my devices.

I mean, even your car, which, keep in mind, is a multi-tens-of-thousands dollar product, exfiltrates your location, all your texts, all your phone calls, and as much data from your phone as possible.

Yes, this is a "leap of faith". I am not bound by a purely evidence-based worldview - I consider that naivety. I do not need strong irrefutable evidence of bad things happening. When people are untrustworthy, I approach them with skepticism in order to protect myself.

For example, I have absolutely no proof that the NSA is surveilling SMS and telephony right now. None at all. But I know Prism was a thing. It is safe to assume the NSA is absolutely surveilling SMS and telephony.

And, I'm almost always right, in my experience.