I thought this article was fascinating: https://www.washingtonpost.com/news/arts-and-entertainment/wp/2016/06/30/taylor-swift-and-tom-hiddlestons-parade-of-love-is-a-gold-mine-for-paparazzi-a-dream-scenario/

The best part for photographers and agencies, besides the money? All the photos have been fairly simple to obtain. When Swift met Hiddleston’s mother in the small seaside town of Ipswich, England, the couple didn’t appear to mind that photographers were following them around on the beach.

“It’s only as easy as [the celebrities] allow it to be,” Ken Goff of Goff Photos said, explaining the challenges of photographing stars. “Because if they had gone there and stayed in the house and not come out, that’s as hard as it can be. So really, whether it’s in a small town or village or in a major city, it can be difficult anywhere or easy anywhere. It just depends on the subject and how much they don’t want to be photographed.”
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None of the agencies would confirm exactly how they find out where Hiddleswift will be next — the Image Direct, which first snapped the photos of the couple making out on the Rhode Island beach, declined to comment.