Most web-sites don't have ContentID - there are companies that scrape the web to find potentially infringing content and file DMCA complaints on content-owners'

Most web-sites don't have ContentID - there are companies that scrape the web to find potentially infringing content and file DMCA complaints on content-owners' behalf. It's much cheaper to just hit Google and a big few like Youtube rather than customize a bot for every site that handles DMCA takedowns.