>Technology executives with authority over contractor requisitions and interview processes can direct substantial volume toward "preferred" staffing shops. In exchange, these vendors provide kickbacks that, in Walmart's case, generated what sources estimate as millions in illicit payments over multiple years.
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The Sopranos was a HBO show about a mob family. Historically, waste management in some cities has been controlled by the mob.
The Sopranos was a TV show about the Mafia. The Mafia is a criminal syndicate whose operations consist primarily of providing illegal drugs, prostitution, and charging companies in their territory for “protection” often from other groups, but also often from themselves. The show had the mafia use a waste management company’s services as a superficially legal reason to be paying these protection payments.
At least that’s my interpretation.
They do engage in racketeering to ensure that they own all the contracts in a certain region, and compete for territory, but they do often actually go and collect the waste, it's not just a front. And I think they did in the Sopranos too, although it was not explicitly depicted as far as I remember, just off-hand references.
The illegal part is in how they get rid of it. Often they take on high-value contracts for toxic waste products that are complex to handle in a compliant manner, and they just dump it wherever.
Obviously, this is quite corrupt; that person is supposed to be paid by Walmart to best represent their interests, not select the vendor based on who will best financially compensate them personally.
The Sopranos part is a reference to a TV show about the Mafia, in which (presumably, I haven't seen it), bribery schemes like this are common.
Mostly illegal.
The biggest kickback exceptions are airline mileage programs and hotel points where employees become incentivized to pick higher cost routes or stays to earn points.