FWIW: I just tried "mazda 5 wiring diagram", and indeed there's nothing good there. But... I think that's because there's nothing good there. I suspect if I really want that document I'm going to have to buy it.
I mean, everyone in a technical field deals with this. There's stuff out there, but it's going to be on some rando adware site with questionable licenses. Datasheets for old ICs. Repair documentation for consumer electronic devices. Even regulatorily required stuff like MSDS sheets for older products tends to not be available in public places.
But the search engine can't fix that for you.
[1] With the notable exception of software development, where open source has freed us from those walls. But also instilled in us the attitude