Basically, it's NOT patent-free, it is completely patents encumbered, but since most usages of AV1 are YouTube, Google will help you defend yourself against suers.
However, make a competitor of YouTube, and I wish you good luck not paying those fees.
With regards to "from people who had nothing to do with development", there are many research centers, not patent trolls, who actually published publicly their researches. Maybe the people who did AV1 didn't read the literature, but I'll presume they did.
> Google will help you defend yourself against suers
They don't indemnify you from patent claims.
They merely offer you the ability to use their patents to help defend yourself. But against the likes of NTT, Orange, Phillips etc patents aren't the issue, it's running out of money to litigate the issue.
However, make a competitor of YouTube, and I wish you good luck not paying those fees.
With regards to "from people who had nothing to do with development", there are many research centers, not patent trolls, who actually published publicly their researches. Maybe the people who did AV1 didn't read the literature, but I'll presume they did.