I don't think that's the case anymore since most people are living in tall buildings and flats, and I doubt each apartment has a safe.
People are still hiding their valuable things but they are mostly using hidden compartments or in walls, and some of them still trust the banks
I honestly don't know many people who publicly say they own safe deposits in their homes and I never saw it myself, but nobody is going to brag in public about that obviously.
Getting back to steel washers, most people do own some basic home tools and steel washers, so nobody would be interested in them very much
Fair enough, maybe it's a cultural thing or location dependant or even a generational thing. I know quite a lot of older people who are totally against banks, and have cash stowed away. They were self custodial-ing before it was cool to do so.
A lot of the olders houses around the UK have built in safes, and they're big bastards. You aren't getting it out without a bit of a struggle, and a lot of noise. Times are changing those, we're moving to the digital money age, and therefore houses don't come with them any more. Honestly, I don't think these new timber framed houses could hold a safe of that weight up anyway.
Yeah, steel washers with your seed could potentially even be left out in a tool box (although probably shouldn't be stored with expensive tools). Since, not many people are going to think twice about that. Not my particular choice of method, but I could see the reasoning behind it. Basically, anyone breaking into your house is looking for electronics, jewellery, and likely a safe of some kind. Since people are creatures of habit, they tend to store these safes in the same places too.