HBO's "Last Week Tonight" host John Oliver closed his Sunday episode by revealing how some of the largest U.S. companies spend millions of dollars busting unionization drives.

Oliver delved into how Amazon, Delta Airlines, Starbucks and Target use “union-busting” tactics to illegally threaten workers. Such tactics include influence campaigns and intimidation, anti-union signs throughout the workplace and multiple anti-union texts throughout the day. Some companies also went as far as showing mandatory union videos disguised as anti-union campaigns.

“If you’ve never been through a union organizing drive yourself, you might assume that a union vote is a completely free and fair election,” Oliver said.

He added that a secret ballot election is “an illusion fed by executives like Jeff Bezos,” who said Amazon didn’t "believe that we need a union to be an intermediary between us and our employees, but of course at the end of the day, it’s always the employees’ choice."

"I don’t know about you, but I’m personally not comforted by hearing one of the richest men on Earth say, 'it’s your choice,'" Oliver said. “No matter the context, all I can hear is, ‘Spear or arrow? How would you prefer to be hunted? It’s your choice.'"

These large companies’ use of illegal intimidation works because there is little repercussion, Oliver claims. They can tell their workers that joining a union might threaten their jobs or make them lose money on the basis that these are mere “predictions” rather than company threats.

“Just to be clear, that is a for-profit consulting firm being paid by a for-profit company arguing that unions are only in it for the money,” Oliver said. “It’s not even the pot calling the kettle black -- it’s the pot calling the kettle a pot. It’s like being called 'a bad first date' by Ted Bundy.”

Though nearly half of non-union workers say they would like to be in a union, just over 10% of American workers belong to one. This is just above half the rate of unionization in 1983, meaning that Americans live in one of the worst times for organized labor.

Oliver became a Twitter topic on Monday for his segment on unionization, with many on social media emphasizing the challenges of forming a union in the U.S.