Ditto. I’ll sometimes say something and other times I’ll just zip by and usually they’ll gasp and swerve over to the right where their supposed to be in the first place. At crowded races like CapTex in Austin it’s just not possible to be yelling “on your left” the whole time. Usually if I’m coming up on them fast I just pass quickly and quietly so by the time they’ve reacted and done something stupid I’m already past and clear of trouble.
The worst is at corners or u-turns where it seems like everyone feels it is necessary to slow down to 8mph and assume proper cornering technique with inside knee up and pointed into the corner. Meanwhile I’ll just dive inside of them pedalling through the turn in my aero bars. (Note: I do not pedal through u-turns nor do I stay in my aero bars… :-))