Thank you for these awesome pictures!!!
To try to answer your question, I think women take only one shoe at one time because...
- It is much less visible: in case of heels, women remain at the same height. In a professional environment such as a store or a fair, some superior would undeniably reproach them with taking off their shoes. Taking only one shoe off is less 'impolite' and harder to notice for a non-experienced eye. I think even women do not imagine that anyone sees what they are doing. On the scale of good manners, dipping has nothing to do with taking both shoes off.
- In the mind of women, dipping is different from taking both shoes off as well. Taking one's shoes off in public is embarrassing and not acceptable according to behavioral standards. I think many women are not even aware of doing so. They try to relieve the pain in their feet unconsciously. They go from a slight heelpop to complete dipping without feeling as if they were taking off their shoes. Because when you still have a shoe on, you're not barefoot.
- If need be, it enables to put the shoe back on much almost instantly and anyway, much more rapidly that if both shoes were taken off simultaneously.
