When an object’s selectability is toggled off in the outliner, the object can still be selected from within the outliner, but is not considered fully selected (I don’t know what this state is actually called so I will just refer to it as “soft-selected”). While in this state some functionality, such as translating, rotating and scaling of the object is locked. This unfortunately also means that the object’s drivers cannot be edited or even seen from within the driver editor. This seems rather unnecessary and forces the user to temporarily re-enable selectability for that object just to edit its drivers.
I believe it would be better if drivers were visible and editable from the driver editor while an object is soft-selected.