But doesn't Usenet require an account that's linked to a payment method? If you use something like a credit card, then the server owner has your real info and presumably a list of every illegal download you've done. Seems like you'd be putting a lot of trust in the server owner, and couldn't it get subpoenaed?
It is safer to use a Usenet provider of a different country.
Secondly and independently, Usenet providers often don't keep very many logs, so there may not exist anything for the server owner to provide in response. For example, if the Usenet provider gets ordered to list all users that downloaded a particular movie, the provider could respond that they don't keep such records.
Also, think of all the pirate streaming websites that exist.
The worst that can happen here is that a court orders someone to pay a fine for downloading something, and this would make big news if it were to happen for Usenet, etc. It hasn't happened to anyone afaik.
Downloading from Usenet is not like downloading from torrents; it is not p2p. One downloads from the Usenet service provider over SSL encrypted connections. There is no way for anyone else to track it.