Because you aren't uploading like you are with torrents. In many (most?) jurisdictions downloading for personal use is ok. It's the uploading that exposes you to legal liability.

It is similar to watching illegal streams of copyrighted content. In most legal systems going after that is either hard or very little reward.

On other hand with torrents you usually automatically upload. And even single uploaded copy can result is some extremely questionable math of potential damages. Which the legal system in essence has blessed.

Easy to see which IP is on a torrent from anywhere (it’s a service you can buy).

Legal differentiations in some places between downloading and distributing.

At least at one point news servers were in a kind of a limbo rights-wise. They were kinda like ISPs providing a service and thus weren't liable.

Just like I can send you a copyrighted image via email and the email server owner isn't liable for the material on their drive.

Also it's hard to track compared to the ease of monitoring public torrent swarms.

With torrents you can just enter the swarm, log all IP addresses and maybe download a bit that it's actually infringing material.

With news the stuff is ascii jumble spread in posts with weird names and you need to download it all to figure out if it's what it says. And just looking for material from the 300TB backlog is a huge pain.