Brand loyalty - some people always buy one make - and stick to it, even though the same manufacturer now produces them all on the same production lines, and only the interior trims or other very small details are actually different.
Similarly, the Explorer group manufacture Compass, Elddis, Xplore and Buccaneer - though there are more 'visible' differences in these makes than in the Swift group. I don't doubt that as manufacturing pressures and costs 'hot up' in the 'credit crunch' that the Explorer group models will also become more similar as costs are cut to the bone.