I think the purpose of the override is to work the other way around. I appreciate it could be used to promote Evri, but really it is there just in case buyers  select Evri for an area they don't deliver to. RM deliver everywhere.

Do you really think Ebay have put enough thought into this to be coming up with an intricate plan to squeeze every last penny out of sellers that way? I mean if they wanted more money they could just have put seller fees up or just stopped the 70 or 80% discounts. Much simpler, much less confusion, software rewriting and little to go wrong. 

Ebay haven't even thought as far ahead as the next RM strike on this one. The whole thing is rushed, badly thought out, poorly communicated and not even implemented in full yet, but that is all. Lets face it, they couldn't come up with a conspiracy and implement it, could they?