I work in the corporate world, I have detailed confidential discussions about technical details of upcoming products and contract details. The first thing we do in those situations is we all sign NDAs. The idea that you'd do a presentation to a hundred people and expect that information to stay confidential without specifically informing them is just absurd. Which is part of the reason Jobs just screwed him around rather than doing what you're meant to do - get the person to sign an NDA and then sue them if they break it.
Pricing details in contracts are trade secrets. You don't even need an NDA to sue someone for leaking that.
They're lucky Apple found a quick remediation. They delayed signing the contract because they had to wait and see if any damage was caused. Next steps would have been renegotiating or lawsuit.
I don't doubt you, but my experience is different.
Every company I've worked for (mostly F500s) has had an onboarding document you sign in which you're notified that everything inside the company is confidential by default. It doesn't expire.
Most of these companies also had annual training (the usual corporate policy refresher stuff) and this was mentioned during that as well.
I've worked on some very hush-hush projects. In my experience, NDAs were for people outside the corporation...partners, vendors, etc. Everyone who was employed by the corporation was under an NDA by default. I don't think I've ever signed a subsequent NDA for something my employer was working on, because I was already under one.
And even if they didn't do all this formally...it's a reasonable expectation. I would never think I'm allowed to discuss anything that wasn't publicly announced with outsiders.