You don't always pay for these articles. Lots of the time press outlets are looking for stories, and PR firms know this. They send a few emails, maybe even give "press releases" that are super close to being an already finished article. The press outlets are cool with this because it helps them get more stories and thus more advertising dollars.

Possibly, but PG's submarines do not directly pay the outlet. Instead, a contact at the hired PR agency contacts some newspapers reporter and gives them something that could be news. Of course, the reporter wants to publish interesting articles, and they trust the PR agency contact, so very likely they will publish some article about that.