Why do search engines show sites of gambling, pornography, and drugs from major tech companies?

The main issue is that some large tech companies have SEO technicians and content rule reviewers who are lazy, or these roles no longer exist. This has been exploited by black-market operators to generate search pages (containing only their illicit content and contact information), which they then submit to search engines for indexing. Leveraging the high domain authority of major websites, they capture search traffic.

Using Douyin and Amazon for Black-Market Keyword Rankings? | Search Page SEO Security Guide