I've read about it before, at https://en.wikivoyage.org/wiki/Avoiding_travel_through_the_U...

Basically, the problem seems to be that the USA does not have "sterile transit"; if your plane stops there in the way to somewhere else, you have to disembark and go through customs, and you need an expensive visa.

Try pricing tickets regularly between Latin America and Asia. My peer groups buys a lot of such tickets and the AeroMexico tickets that fly with a change of planes in MEX and go on to PVG and NRT with no USA transfer cost about US$500 more than tickets that change planes in LAX, SFO, DFW, and SEA. YVR is usually priced in between but sometimes Air Canada has deals.

There are no other flights directly between Asia and Latin America (unless you count the EK GRU-DXB flight), though NH may be flying to MEX soon.

Flying in the US is a consistently miserable experience. Airports which are too small for the number of flights they handle - leading to cascading gate changes and flight delays, slow & interrogative customs which you must go through even if you're getting a connecting flight straight out of the US, obvious complaints about the TSA and airlines who all (apart from Southwest in my experience) really just have no interest in making flying a pleasant or comfortable time for you.

On my most recent trip to the US I selected cities that I could get between via train to avoid the entire mess apart from arrival into the US (and made an effort to depart out of Canada).

US airlines are doing fine now that fuel is almost free. We'll see what happens when oil prices rise again.