Well, unfortunately, corruption is everywhere - especially now. WWP probably paid them for that rating after their bad publicity when their scam was on the news.
Another example: Here in Los Angeles, they adopted a Rating System for restaurants & markets. They assigned a letter grade - just like schools use - A, B, C, D, etc. The grade was based on inspection results from the Health Department. And the grade had to be posted on the front window.
Several Health Inspectors were making a FORTUNE selling "A's" to restaurants - many that failed inspection. The ones that were caught were arrested & charged.
https://www.latimes.com/archives/la-xpm-1998-nov-11-me-41653-story.html