If you refer to a passenger in a car as a backseat driver, they annoy you because they constantly give you advice about how to drive.
[disapproval]
2. countable noun
If you refer to someone, especially a politician, as a backseat driver, you disapprove of them because they try to influence a situation that does not concern them.
[disapproval]
They accused the former president of being a backseat driver.