At a later date, private phones became the norm. And so in Katz v. U.S. decided in 1967, warrants for tapping phones were held to be required. That is because people's expectations of privacy had changed.
In the case of TOR, people were using a service that was advertised as being designed by the NSA to protect your online privacy EVEN IF you were under attack by state actors. In fact it was widely advertised that all anyone could know is that you were using TOR, but nobody would know what you were doing with it, who you contacted, and so on.
What do you think would have been a reasonable expectation in 2014? That using TOR meant your communication was private, or publicly available?