I spent some researching this because of running across a situation, whereby, I found myself stuck behind people turning over a double yellow line from the left turn lane right at the traffic light into a Wendy's in Boone, NC. What I found was that it is considered legal to make a left turn over a double yellow line into a drive, ally or store entrance, however, as long as you can do so safely and NOTE:
without impeding or
obstructing traffic.
In my case, the Wendy's drive entrance was right on the corner of the intersection across 2 double yellow lines of 2 lanes of oncoming traffic from the left turn lane. Also, unlikely the person trying to make the left turn from the left turn lane at the light realized when we get the green turn arrow to go, the right turn lane of the cross traffic gets a green arrow also to turn right. Obviously, this makes the person trying to make the left turn into Wendy's unable to do so, due to to the constant flow of cars turning right.
Mean while, everyone is held up from making the left turn light because of this person insisting on a left turn against the on ongoing traffic turning right.
So I honk to encourage the driver to continue through the left turn light and let us all make our left turn.
But no! They insist on making the left turn edging forward and stopping as cars turning right continued.
Finally the driver was able to make the turn just as the left turn light turns red and none of us made the left turn signal.
This is a perfect example of illegal left hand turn over a double yellow line. Also, a perfect example of being inconsiderate and indifferent to others on the road.
The LAW is left turns over double yellow lines are permissible IF they can be done safely and without impeding traffic.