Why is bargaining more common in poor countries? In poor countries, one might bargain over even say a bottle of water. This is unthinkable in most rich countries. (And in countries that develop rapidly, one can actually notice the steady movement from bargaining to fixed prices.)

The "obvious" explanation is that time is less valuable in poorer countries and so people (both buyers and sellers) are willing to spend some time bargaining.

But I wonder if there have been more in-depth attempts to understand this matter (empirical and theoretical).
In first world countries, the price of a bottle of water is set by a well-established market. There are millions of prospective buyers of a bottle of water and thousands of prospective suppliers, and while many suppliers are able to achieve brand differentiation, for the most part their water is fungible. Moreover, the supply and demand curves of water are reasonably stable, and water companies have the excess capital to hold inventory stockpiles that further reduce the volatility of prices. There is little information asymmetry. Customers can easily comparison shop, and price discrimination is very difficult. Suppliers are generally large corporations, which means that allowing bargaining would introduce massive headaches, such as agent-principal issues. There's also a feedback effect: once an economy and culture are built around fixed prices, it's more difficult to introduce bargaining. Water companies are in a low-margin business where their money comes from high volume. Spending resources bargaining would destroy those margins.