Without space equally enabled it seems like every minority is approaching a majority. I'm not sure what the point of the setting is, as its certainly not accurate.
The default view shows the relative number compared with the average.
If London has more minorities than the rest of the country then they will all show as blue.
It is accurate, just potentially a little misleading.
It would be useful if there was an option to calibrate things for just the area you have on screen to get a better idea of variations in a particular area.