Don't you have to be participating in the conversation? Our state' single party consent specifically excludes "walk ups" and "back grounders". For instance a waiter at a restaurant cannot record a table's conversation just because he said a few words. Also a person cannot say "hello" and then quietly sit by and record you.
The person doing the recording must be an active and constant participant in the conversation, otherwise the recording is illegal.
Not in my state, and not by most two party laws. This is VERY specific and clear in my state: The driver is outside the conversation.
By your rational a police agent without a warrant could walk by and say "hello", plant a listening device, then record your conversation because he said hello at the start. This is specifically not two party (I spot checked several state laws). It would be illegal in many states (mine included).