Different societies have different attitudes towards footwear. For example, in India footwear is not allowed in most places of worship, doctors’ clinics, and even some small offices and places of business.
On the other hand, the footwears of some divine personalities are revered. The most classic example is Bharata placing Rama’s padukas on the throne as proxy.
In Sikh Gurdwaras devotees clean other devotees’ footwear as a kind of seva.
Another thing I notice is that whenever we leave the footwear outside as a group, it is always in a clutter, not in a row. I have seen Japanese and other tourists leave their footwear in a neat row outside Indian monuments and places of worship. Is this a culture thing?