Dear anonymous,

your comment does not help to improve openstreetmap data.....

maybe someone with more knowledge what's on the ground than we both will read this comment and will be able to contribute something useful.

A bit of information: the change 38296743, where the highway type was changed, gives "bing" as source - but I have strong doubts  that you can distinguish from an aerial image if a road is a motorway or a primary. 