Why is it that in a monopoly, some trades don't happen even though it would benefit both parties?

Question

Why is it that in a monopoly, some trades don't happen even though it would benefit both parties?

Answer 1

For the same reasons that trades don't

happen even though trades would benefit

both parties even if neither is a monopoly-

perhaps, even though both parties could

benefit, one or the other or both parties

could benefit more by entering a different

trade or by waiting 'til later. Also, local and/or

international rules and/or regulations could

be factors.

Answer 2

that such trades don't happen seems to be an assumption rather than any fact