You aren’t turning the statement of account into a BOE, you are completing it by filling in any missing particulars (including a sum certain value) and countersigning it. You then attach valuable consideration to form a contract. This could be a BOE or promissory note (or even a check or cash).
If you are using a promissory note you wouldn’t put “drawer” on the statement of account that you are re-negotiating, you would put “maker” as Promissory Notes are 2 party instruments involving a Maker and Payee.
A sum certain is just a more certain value, which is usually in writing and the lesser amount. You can make mistakes when writing figures so a more certain amount is in writing (ONE HUNDRED DOLLARS).
As for why they don’t just have Sum Payable… My guess is what I wrote above or that they have to provide a remedy to us peasants (albeit a hidden one)?
It doesn’t need to be $1 either, it can be any value. $1 is the minimum amount of consideration needed to form a binding contract. You could nominate other values if you wanted.
As for the securitisation, I am not sure. I have also wondered this. If it is not negotiable I assume they could only securitise it for a $1? This is why Promissory Notes could be better in some cases because they can get the whole amount (usually you add 20% on top of what they are asking).
The $1 is just to level the playing field and to stop these parasites with their unjust enrichment.
At the end of the day it is your signature that gives anything value. So I am not sure if this allows them to dip into your Trust account and get credits or what?