Copyright enforcement is actually quite expensive, both for the litigant and the defendant. The only way for it to be actually profitable to sue someone who is stealing your work is if they immediately settle, which is how copyright trolls operate. Everything else is a massive money pit for everyone involved, even the lawyers. Since this is an international enforcement action, the costs go up more, because now you need multiple legal teams on the bar in each jurisdiction, translators qualified for interpreting laws in foreign languages, knowledge of local copyright quirks, and a lot more coordination than just asking your local counsel to send a takedown notice locally.

(Just as an example of a local copyright quirk that will probably confuse a lot of people in the audience from Europe: copyright registration. America really, really wants you to register your copyright, even though they signed onto Berne/WTO/TRIPS which was supposed to abolish that regime entirely. As a result, America did the bare minimum of compliance. You don't lose your copyright if you don't register, but you can't sue until you do, and if you register after your work was infringed, you don't get statutory damages... which means your costs go way up.)

Furthermore, every enforcement action you take risks PR backlash. The whole fandom surrounding import Japanese comic books basically grew out of a piracy scene. Originally, there were no English translations, and the scene was basically reusing what we'd now call "orphan works". There used to be an unspoken rule among most fansubbers of not translating material that was licensed in the US. All that's changed; most everything gets licensed and many fan translators absolutely are stepping on the toes of licensees. However, every time a licensee or licensor actually takes an enforcement action, they get huge amounts of blowback from their own fans.

They get plenty of takedown notices, but they mostly get to hide behind services like Cloudflare who won't take action regarding these notices anyway. From the publishers/creators side, there is simply no effective way to take scanlators down.

I suspect it's because the international market for print manga (the primary cash cow) is rather anemic, particularly compared to anime.

Publishers see the loss as minimal and creators see piracy as free advertising to drum up enthusiasm for anime adaptations, which actually do drum up decent profits internationally (the committee keeps the streaming licensing fees, not the animation studio).

Publishers definitely don't see it that way; that's mostly an extension of a myth in order to justify the piracy.

Most manga publishers will see relatively little revenue from international anime releases. Even for domestic anime releases of the vast majority of titles, the manga publisher is only a small part of the anime production committee, and the hope is mostly that popularity of the anime can lead to increased sales of the manga, merchandise, or other events. So when the anime is released internationally, they get an even smaller cut of that because the international licensee also has to take their profit.

But other than mega-hit titles where an international anime release may also lead to significant international manga sales, the popularity of an anime adaptation overseas is practically irrelevant to the original manga publisher.