While the TOR browser may provide some anonymity, it is only as trustworthy as the "relay networks."
They claim:
a ""free"", worldwide, "volunteer" overlay network consisting of more than "seven thousand" relays
If you understand how BGP protocol works and how the DNS name servers are architected and how major carriers share co-located points-of-presence you would not feel so reassured.
Since about 1% or less of the population understands these basic facts (public info to too complicated for mere mortals), your next best bet is to consider the TOR description
world -wide
free
7,000 sites (or multiple devices at fewer sites)
It takes equipment, bandwidth and high-priced expertise to manage this, somebody is willing to "volunteer" all that infrastructure and expense to give it away for free and with a free browser.
No apparent financial benefit but a tangible cost.
Who provides these 7,000 nodes for free and who has the expertise to manage that part?
Honeypot? - Look it up if you don't know what is is.
Think about phishing - why do people voluntarily
click those links?
Answer: trust (who do you trust to secure your communications)
My contention is not that it is worthless, and likely useful to keep out the amateur hacker-wannabees, Traceroute wizards,etc. but am infinitely convinced it would not be difficult for a large number of organizations, that already have some access to the Internet infrastructure
Any 3-letter agencies come to mind?
Any service providers?