My headcanon for The Matrix's "humans are batteries" is that it's the machines' perverse interpretation of this
killing the humans is off the table, and for whatever reason letting them live with no purpose to serve the machines is also disallowed. But giving their lives "meaning" in the form of a shitty (and thermodynamically dubious) "battery" somehow satisfies the rules.
It's a very big stretch, I'll admit...
Awesome bandwidth to be sure, but I do think there is a difference between data transfer to RAM (such as network traffic) vs. traffic purely from one location to another (station wagon with tapes/747 with SD cards/etc.).
For the latter, actually using the data in any meaningful way is probably limited to read time of the media, which is likely slow.
But yeah, my go-to would be micro SD cards on a plane :)