I think "most" don't understand, and it would be my wager why providers aren't using phrases like "RF spectrum" and "3 Mb/s for the first 2 GB transferred per billing period".
Providers actually do know people are dumb and frightened by complicated explanations and technical jargon. I know because I've had to teach customer service training classes to prepare tech support Reps how to *not* use technical words and phrase when explaining problems to customers because they inevitably lead to frustration, confusion, and irate customers. That's right, *training* in order to dumb things down for customers. This is a real job.
When you're smart, you're inclined to think most other people are sort of smart too, more or less. Truth is a LOT of people barely understand how an internal combustion engine works, much less how the magical internet gets to their phone, their PC, their Xbox, and whatever else shiny gadget they are told to buy. Don't believe me? Go to a store or mall with a clipboard and ask people "What is a gigabyte?" and/or "How does wifi work?" People don't care or understand how most modern devices work, as long as it *does* work.