To be fair, Otto's not alone. Engineers at Google have also been spotted in T-shirts with the slogan.

One of Uber's early self-driving car rides in California went viral last year after a vehicle rushed through a red light on video. Bloomberg reported that the recent snafu with Uber's self-driving cars "came as no surprise" to Uber employees who had visited Otto's headquarters:

The slogan "Safety Third" was reportedly passed around as punchline at self-driving truck start-up Otto, owned by Uber.

But Otto's co-founder Anthony Levandowski is now on the front line of a battle between Uber and Alphabet's self-driving car company, Waymo. Levandowski stole Alphabet trade secrets when he ended his employment, Waymo alleges. Uber calls that claim "baseless."

"We will have a chance to tell our side of the story in upcoming filings and look forward to that opportunity," Uber told CNBC. Waymo did not immediately respond to a request for comment.

Uber's Pittsburgh team was "super unhappy" when Uber announced its acquisition of Otto, an unnamed former employee told Bloomberg.

Levandowski was a polarizing figure at Alphabet, too, Bloomberg reported: "He was so controversial, according to several former and current employees, that when he was being considered to lead the car team, a group of engineers revolted."

Indeed, while at Alphabet's Google, Levandowski hired a lobbyist to write a state law on self-driving cars — a law that Google found out about when it got the bill from the lobbyist.

But Alphabet executives are also worried they are falling behind companies like Uber, the report said. Waymo CEO John Krafcik is rattled "every time Elon [Musk] would post something on Twitter," the report said.

To read the feature on the "vicious patent fight over self-driving technology," see Bloomberg.com

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