What I’ve found is with american or british companies you’re more likely to come across someone who just kept everything. Just took it all home and kept it. With Japanese companies, for a long time older stuff was destroyed to protect trade secrets, et cetera. The only reason SNK kept all that art they had is because they knew they could use it to sell art books.
I suspect there’s lots more floating out there in japan, but finding the right people and getting them to give up their stuff is very difficult. Also the vintage game community there is much more insular, not wanting games to be dumped and shared, to a much greater degree than you see here. I think there’s a perception of western folks coming in and buying up all the games and driving up the prices, which makes people want to guard their treasures.
Overall the biggest difference I’ve seen is there has been a wider culture of sharing information about game development in the west, through publications like Game Developer magazine and blogs and whatnot. In Japan even through the 360 era they’d have two teams in one company working on different codenamed games and not allowed to share resources or talk to each other about it. I’m sure they did talk! but the fact they weren’t supposed to changes a lot of things.
I’d say Japan does a good job of looking forward with finished products, and seeing how they could reheat that for future generations. but when it comes to stuff that never came out, or older documents, or things like that, there’s no company-level preservation, and it’s more frowned upon for individuals to take the stuff home themselves, so it’s tougher to find. In the US there’s no company-level preservation either (more now), but you sort of expect someone to have taken all the design docs home before they got thrown out… or something?
The guy with the warehouse doesn’t have foresight - he just has a big warehouse and a desire to be able to rent everything (his business is as a rental service for arcades, so the more games he has, the more he can rent out). What I have found in Japan is that preservation largely surrounds whether there’s a business reason for it.
But at the same time, the tokyo diet building had scanned archives of every magazine we could ever want, which we were able to send someone to in order to get ads so that we could place the release dates of games. So it’s kind of a mixed bag and you just have to sort of navigate it!
I’m not sure if I’ve really answered your question 😛