I wonder if there is a dataset of protected left turn (a left-oriented arrow) traffic signal? For example, a GIS dataset of the location of traffic lights that have this signal.
I thought this information should be essential and easy to be found. However, after I've looked up many detailed traffic signal datasets (data.gov, OpenStreetMaps, and GIS open data websites), none of them seems to have protected left turn signal information.
If there is no such dataset, what would be the rationale of lacking such data? US data preferred.