You bargain for what you're trying to buy at the local markets in much of Asia. In the west, this is virtually unheard of except for special items, like cars. Was bargaining once the norm in the US and Europe? When and why did it fade away?

I'm going to assume that by "bargain" you either mean to "barter" (use a good or service of your own to pay for another good or service in return) or most likely to "haggle" (to have a discussion about the price that will be paid). If we're talking about bartering, I'd imagine that most if it began to rapidly fall out of style around the time of the invention of the US dollar in 1792, since you now had the ability to pay for things with a universal currency with local, but that's excluding Europe from the discussion.

All told, I think that regardless of the meaning of bargain in your question, the answer is quite similar - Villages turned into towns and cities, while businesses became standardized and widespread. It's believed that the first ever chain stores started off with J Stiner and Company in 1860, which is a good mark for when "bargaining" began to fade away. This is because large store chains are the antithesis to an environment that encourages haggling or bartering. Bargaining is still common in much of Asia for a variety of reasons, but it's no coincidence that Asia also has many large "open markets" that contain many sellers and buyers who do not operate on behalf or in conjunction with larger entities, like corporations and businesses.

In comparison, the USA and Europe have developed into quite different paths from Asia - standardized businesses and chains are the norm. Now, worth noting, in parts of Europe it wouldn't surprise me if there were still markets that operated similarly to Asia, but I couldn't find much concrete documentation for it being widespread within the region anymore.

So, in conclusion - you can point to roughly the 1860s as when chain stores and larger stores hit the scene, and with them followed the death of widespread bargaining. Of course, as a resident of the USA, I can tell you that there exist many smaller sellers who might still "bargain" with you, but no source documents any ongoing markets like in Asia still existing within America.

References:

Marc Levinson, The Great A&P and the Struggle for Small Business in America, 2nd ed (2019), p. 14.