The trauma of the financial crisis may have permanently changed Americans into frugal cheapskates, theorizes CNBC "Mad Money" host Jim Cramer. That's a fundamental shift that as huge implications for stock and bond markets.

Americans feared economic catastrophe during the crisis. The country was "a heartbeat away" from the second Great Depression and people speculated about ATMs not working and paychecks not clearing.

That fear seems to have scarred the American consumer. How else can you explain the recent drop in interest rates, Cramer asks, noting that the 10-year Treasury fell to 2.5 percent. "That shouldn't be possible. It's like a square peg being able to fit into a round hole."

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Normally, stocks rise when rates fall. This time stocks also fell. When rates fall nowadays people say it's a sign of an imminent recession. "That's the wrong conclusion people," he stresses.

The view that declining rates foreshadow recession is wrong, he says. "I think America has gone frugal since that near death experience."

In that way, Americans now are like earlier generations who lived through the Great Depression, banks are afraid to lend, consumers are reluctant to borrow or spend more, home buying is way down and many people, including married couples, are living with their parents.

In addition, Cramer notes, "People aren't having kids the way they used to. Perhaps because they think they can't afford them."

"There's still plenty of renting going on. That's what you do when you're afraid to buy."

While he acknowledges that consumers are buying more cars, Cramer argues that they need cars to get to work.

A recent survey by Deloitte indicates that Cramer is right about the new frugality.

According to Deloitte's annual survey of food shoppers, 94 percent of consumers say they'll stay cautions and not increase their spending even if the economy improves. The figure changed little from 2010, despite an improving economic picture.

Consumers "have gotten really good over these last four years at stretching a penny," Pat Conroy, head of Deloitte's U.S. consumer products practice, tells Reuters. "Our hypothesis was that this thing was going to leave a scar, not a bruise. So far, we've been right."

Although food retailers and restaurants must raise prices due to rising costs of products like milk and meat, they're being careful to control costs and justify prices increases, according to Reuters.

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