I'd be interested in seeing the dictionary that defines the prefix "co-" as somehow not involved, a mere bystander. The basic understanding that every dictionary I've ever encountered is something along the lines of;
co-
prefix
1. together; joint or jointly; mutual or mutually; coproduction
2. indicating partnership or equality; cofounder, copilot
3. to the same or a similar degree; coextend
4. (in mathematics and astronomy) of the complement of an angle; cosecant, codeclination
(from Latin, reduced form of com-)
Which dictionary is that?
It is also not correct to state that the prefix “co-” is derived from the Latin “cum.”
“Co-” is a Latin prefix on its own and can imply subservience, authority or parity, depending on the word to which it is attached and the context of the statement.
Reference:
http://www.archives.nd.edu/cgi-bin/wordes.exe