People tend to forget, and might I say with good help from the advertising, that depth of field becomes largely independent of focal length when you get into the close-up region. Thus we should NOT think of a 'macro' image with background in focus, as this is not possible (except using camera/lens movements, but then the issue is with the objects taller or lower than the intersection of the focal plane to the subject).
Instead it's about the illusion created by a background blur with smaller circles of confusion. Thus the background with a short focal length lens will not look as a pure wash of colours, there will be unevenness to it and in some cases the eye 'resolves' enough of the blur to identify some part of the background. However, by no stretch of imagination the background will become 'in focus'.
