That's mostly because it was revived, relatively recently, from Playford; it didn't survive in tradition.

Although the tune can be made to fit 'Cam'st thou not from New-Castle', there is no evidence that they really belong together. See Claude M Simpson, The British Broadside Ballad and Its Music, 82-3; where Simpson comments "The trimeter quatrains are so lyrical that is difficult to accept the forcings necessary in putting them to the dance tune. In all likelihood the surviving tune is not the one which must have had some currency in Elizabethan days and in the early part of the seventeenth century".