Mrs. Vandebilt

When Paul McCartney and his Wings launched their *Band on the run *album, the first single in Holland was Mrs. Vandebilt. It made the top10 and is one of my favourite Wings songs. To my surprise, it did not make it to the Greatest Hits compilation some years ago. More annoyingly the double CD Wingspan also omits this song, although it incorporates a lot of rather unfamiliar album tracks. I don’t get it. Is there any reason for this omission? (Google did not help me on this either)