It prevents the illegal distribution of copyrighted material.

I repeat how does that keep anyone safe?

By enforcing the copyright laws that exist already to protect content creators from being counterfeited and ripped off by illegal scammers and bootleggers. Are you saying you don't agree with the concept of copyrights?

How does showing Lion King at your kids birthday party qualify for any of that?

I know I know, Disneys inability to collect money for every pair of eyes watching their movies during VHS times literally made it one of the poorest companies on the world. /s

Does this mean you don't support copyright?

Do you support mandatory cavity searches after every shopping trip? Property laws are important, you should do your part to uphold them.

I think this kind of client-side hashing and comparing to a database list is similar to the scanners at every Wal-Mart and the procedures at airports.

I don't remember airport security scanners at my local supermarket.

I think that fits into the category of the Wal-Mart scanners which are at many stores.

Lots of people don't support copyright. It's a concept that should be abolished in it's current form. Right to attribution is OK. Ability to restrict other forms of use is not OK.

Does that mean if someone spends time and effort writing a book or painting a picture that I can resell it for less than them without their permission?

Why would any fan of someones work buy a knock-off copy? We can safely assume they are a fan, otherwise why would even buy it?

Also, painting is a physical object. It's a one of a kind.

EDIT: your objection and many many other questions like that are nicely argued against here: https://www.youtube.com/watch?v=mhBpI13dxkI (The Surprising History of Copyright talk by Karl Fogel)

Do you think people will want to create new stories if others can undercut and sell their work for less?

Yes. Definitely. Absolute staggering majority of people writing books don't sell even one copy. And my bet is - they know what are the chances.

EDIT1:

More than that. People don't live of royalties. Publishers do. Can people create without being paid upfront by publishers? Obviously yes. They can be paid upfront in kickstarter-like arrangement. They can be paid via donations later. They can even be paid via "retroactive funding of public goods" [0]. Or they can be never paid - just as they are today.

[0] - https://medium.com/ethereum-optimism/retroactive-public-good...

EDIT2:

Also, imagine how much good could come of long-standing IP properties owned by Disney if not for them sitting on it. Vide disaster that is current management of Star Wars.

Do you know how many stories cannot be published because people sit on the IP? There are unpublished "movies" that only exist to maintain exclusive licensing deals that outright prohibit studios from sitting on the IP, letting the original authors work rot until it is forgotten.

Or we can talk about the mess you get with too many groups involved? Do you know who has the rights to Westwoods Dune? Westwood itself had a limited time license for games based on the movie Dune, which also had a license based on the Dune books. So you would have to deal with three license owners to make a Game involving the Ordos faction. Have fun convincing EA, whoever owns the movie rights and the original authors family that you can make a new game worth their signature on a new licensing agreement (you could probably manage if you have a small country to sell).