Would you help us settle this mild marital disagreement were are having about turn lanes?

We often turn right off of Main Street, onto 10th. Main Street is a 4 lane. When turning right, I move into a far right lane that I think is there as a turn lane, although it isn’t marked as such. The boundary is a solid white line, room enough for a car, but there is no arrow indicating a right turn.

There are stop lights over the road for all 4 regular lanes AND an additional stop light on a pole in front of what I think is a turn lane.
There are several streets like this, unmarked but with their own stop light. I’ve told Rick that every one else uses them as turn lanes, and he could get himself into trouble some time by turning from the regular lane and crossing across the turn lane, if someone else is there.

What say you?