This still seems complicated for the average joe and maybe could be presented in a simpler way.
Does the Average Joe even need to know much of the details of the technology? I'm assuming he will be introduced first to BitUSD and will learn that these are digital units that function much like USD, and they can be transferred around the world, they hold virtually the same value as USD, can be stored in a prepaid card or wallet, and on top of that can earn a yield.
At that point, most average joes won't even really care about the background technology. They may not even need to hear the word "Bitshares," as long as they believe BitUSD is sound, closely tied to USD, and does what it's supposed to do.
Then, for the more inquisitive average joe, an explanation of the technology could be given. This should focus on the features of the technology that are most important for the soundness and functioning of BitUSD. It could be presented in a Q&A format.
E.g:
How do I know my BitUSD are safe?
BitUSD is backed by a supply of digital units called Bitshares. Each BitUSD is fully backed by the equivalent value in Bitshares. The value of the bitshares to BitUSD varies to ensure that BitUSD is closely tied to the value of the dollars. In fact, BiTUSD is backed at all times by at least 3x the value, etc.
How are BitUSD transactions processed?
All transactions included on a public ledger, but your privacy is maintained.
A group of 101 democratically elected Delegates around the world cryptographically sign blocks, making transactions transparent, non-forgeable, irreversible.
How do BitUSD earn interest?
From transaction fees, etc.
Is BitUSD similar to Bitcoin?
It is similar to Bitcoin in that it is based on "blockchain" technology that records transactions in a tamper-proof public ledger. But the underlying bitshares technology is different because of X, Y, Z, permitting faster, more secure, less socially wasteful transactions, etc....
The above are vast oversimplifications, but the point is that most of the bitshares technology features could be organized under three or four basic questions that the average joe might have about BitUSD.
Using the Q&A format rather than listing the features of bitshares one by one may be an effective way to touch upon the key technology features of Bitshares without overwhelming the average joe.