While I appreciate your feedback, the Wiki page you reference seems quite clear to me, and while U-turn is not mentioned specifically, they do describe :
Canal Road (Hwy 121) is a dual carriageway physically separated by a canal. The physically channelized turning lanes (or U-turns) are all tagged as links. This is convention throughout Thailand … if you do not agree, please state your reasons on our forum, and allow us to comment. If we support your interpretation, I trust you will assist us in changing every other instance in the country. Trawling the Thai map, I accept you may find other links incorrectly tagged, but this would be down to new users, or very old data.
Furthermore, the table https://wiki.openstreetmap.org/wiki/Link_roads_between_different_highways_types seems quite clear, in that the connection between two primary roads takes the primary_link tag. We adopt this convention in Thailand, and hope that others who are not local, respect our established conventions.
Yes, the way you highlight here does carry a street name, which I agree, is not appropriate, and will be removed.
However, while on the subject of 2 Chiang Rai Road, just why did your organisation change it from Unclassified to Residential, given the fact its bounded on one side by the University and the other by predominantly copy & coffee shops ? Its a significant connecting road which to some, they might argue as deserving Tertiary status, rather than a downgrade as Nathan saw fit.
The point is Kaart, we welcome improvements to the Thai map, but we bitterly resent organisations just coming in and changing existing data, when we have already determined the tagging for a particular way. OSM is about respecting others work, and I encourage you to view the history of a way before making significant changes, and if the determination was made by a longstanding and experienced local mapper, please have the courtesy to contact him first.