Bee tongue lengths vary considerably which means that some bees prefer open flowers so that their shorter tongues can more easily reach the nectar and others with longer tongues can have more exclusive access to tube-shaped flowers.
Honey bees are among those bees with shorter tongues, measuring c.6mm in length, which is still about half their body length but short by bee standards. Compare this with the 'garden' bumblebee, Bombus hortorum, with a 15mm tongue although it is a bigger bee.
Sometimes the shorter-tongued bees employ a sneaky a trick to get at nectar in deep flowers; they go to the outside base of the flower and make a hole to stick their tongues through and steal the nectar. I say 'steal' because this method bypassing the flowers pollen sources and stigmas and so the flower will not be pollinated.
I noticed this behavior and managed to capture it on some rocket that we had let go 'to seed' in the veg patch. In this case the flower petals seem to have a gap between them that allows the honey bee to get through without making a hole but the pollination is still by-passed.