When Delta Airlines charged Marie Duggan, an economic historian visiting Oaxaca, Mexico, $1,200 to change a scheduled flight to the United States, she was so angry she cancelled and booked a cross-border nighttime bus ride instead.

Duggan thought Delta’s price increase to fly to Phoenix instead of San Francisco, at twice the price of a one-way flight to Phoenix, was an insult and a rip-off. So she took a $250 flight on Aeromexico to Hermosillo, in the north-western state of Sonora, and then a $59 bus across the Mexico border.

Sonora is on the US state department’s ‘reconsider travel’ list because of terrorism and crime, Duggan acknowledged, and she was “exhausted” after the trip. But she was also pleased not to have to pay Delta the money. “I thought, ‘Ha! You think I have no choice, but I know that there is a bus,” she said in an interview. “So I will slip out of your grasp.”

A Delta spokesman said that, like the rest of the industry, it relies on “dynamic ticket prices” with “clear rules that determine pricing based on objective details”.

For the past 100 years, US consumers have powered the US economy, their $21tn in annual spending supported by the business ethos that the “customer is king.” Today, that idea is as outdated as a Norman Rockwell painting, say consumer activists, historians, analysts, executives and customers themselves.