https://arstechnica.com/tech-policy/2017/03/doj-drops-case-a...
They run massive PR campaigns with carefully structured press releases designed to convince the kind of people they want to detain that TOR is private and safe for any kind of activity.
Because of this people tend to get swole when you suggest that TOR is not any good for protecting your privacy because lots and lots of people have been arrested, tried and convicted after trying to use it to hide elicit activities.
The US government has made millions of dollars of investment into TOR:
https://www.theguardian.com/technology/2014/jul/29/us-govern...
Pretty much every time the US government is investing in something you can be certain that their intention is not to help you out.