Most breads are baked with speed of production in mind. The 'No Time Process' or
Chorleywood Process dominates the UK market and special wheats and milling processes produce the flour to which other things are added to practicaly eliminate the time reuired for bread dough to rise. Steam injection and flash toating give the fluffy rise and appearance of a crust.
So called healthy loaves still aim for high speed production and this soft spring texture.
Real bread is either quite solid or takes a long time to rise. Good quality breads might be 3 days in the preparation. A real spelt loaf or rye loaf, that is one where most of the flour is spelt or rye, will be less processed and heavy. They are not springy loaves. Both are relatively low GI.
But, there is much marketing trickery and Waitrose mixed wholegrain only contains 6% wholemeal flour, 53% white flour and 41% of other stuff, see
A Wholegrain of Truth.