Sometimes I copy/move from A to B, while I'm moving files/folders within A or within B only. These operations could run immediately, because it's only moving on same drive, but DO puts them into queue. Maybe queue could be optimized for moving-operations within same drives.
I think it's only the ones with B as a destination which would get queued by default. We don't really want to make the automatic queuing more complex than it is as it can never be perfect (it'd need some kind of AI) and complexity would quickly turn into bugs and unpredictable behaviour.
You can manually run queued jobs as well as switch to manual queueing if the automatic mode isn't doing what you want.