What one banker's little scam says about Wall Street

Should the British Financial Conduct Authority have banned a banker from participating in the finance industry for cheating on his train tickets? I'm not sure.

But I am sure that his little scam is a mini-version of all the big scams that rocked Wall Street.

Passengers disembark a train at King's Cross station in London, Nov. 7, 2014.
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Passengers disembark a train at King's Cross station in London, Nov. 7, 2014.

Here's what happened: A British banker named Jonathan Burrows found a clever way to cheat on his daily commute. In London, you have to hand in a ticket or swipe your transit card, called an Oyster Card, at the end of your Tube ride. But Burrows started his commute at a station without a card reader, so he was supposed to buy a ticket. But instead, he boarded the train without a ticket, and when his commute ended at London Underground stop, he tapped his Oyster card on the way out. Since he hadn't tapped in, his card was charged with the maximum Tube fare, about $11, instead of the $34 he owed for his full train fare.

He was caught by the train company and settled for about $67,000.

Read MoreDoh! $67k fare-dodger banned from finance industry

The British Financial Conduct Authority banned the former Managing Director at BlackRock Asset Management from any regulated activities, saying: "His conduct fell short of the standards we expect. Approved persons must act with honesty and integrity at all times and, where they do not, we will take action."

This isn't a big story, but unfortunately for finance industry, it confirms a lot of the stereotypes people hold about how Wall Street or The City work:

1. Bankers believe rules apply to other people. Clever people figure out ways to game the system. Don't like the Libor rate? Fix it. Don't want to pay your train fare? Game it.

2. Bankers don't worry about breaking the rules because the authorities aren't smart enough to catch them. Prosecutors must thank their lucky stars every day for invention of email. How else would they have learned that Goldman's Fabulous Fab Tourre was bragging about selling toxic assets to "widows and orphans?" Those of us who cover the financial markets are constantly surprised at how often financial scamsters brag about their misdeed in emails.

Burrows also left a paper trail of his mini-scam by using his Oyster card. He just didn't think anyone would look.

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3. Bankers don't worry about right and wrong — just making money. SAC Capital pled guilty to insider trading and paid a record $1.8 billion to settle with the government. But here's the thing: SAC founder Steve Cohen is a legendary trader. Perhaps the most successful of his generation. SAC averaged returns of more than 25 percent for two decades and had about $15 billion under management. Cohen was superstar of the financial world. Now, he will go down in history for paying the largest fine in U.S. history for insider trading. Why would a company that was so successful throw it all away for a few stock tips which prosecutors say earned the company about $275 million in illegal profits? Peanuts for SAC Capital.

Read MoreNew insider trading rules make it 'easier to cheat'

Burrows threw away his career to save about $20 a day in train fare.

I know that Burrows is just one bad apple and in no way represents all the honest, hardworking people in the finance industry. But I can't help thinking how his little scam is so much like the bigger scams that nearly took down the financial system.

Commentary by Ellen Egeth, assistant managing editor at CNBC. Follow her on Twitter @EllenEgeth.