Is a movie prop the ultimate laptop bag?

> For me, the ultimate laptop bag is one that looks nothing like a laptop bag; it should look like nothing special at all.

That sounds like almost any regular backpack then. They can also be pretty weather proof, don't need to be carried in one hand, aren't open topped showing what's inside easily, and padded. Any simple and cheap backpack would solve this exact problem but better surely, unless your desire is to be different rather than just to move your laptop from one place to another with little ceremony.

> regular backpacks look nothing like a laptop bag

You're missing some context here — this is in San Fransisco.

I always wonder why no one invented hoodies or jacket with some kind of built in laptop pocket in the back.