The US does not have them, and they are not legal. I agree that they could be useful. But in the US you have strictly two options- represent yourself to a court, or let a bar-certified lawyer represent you. Nobody else gets to help in court. Outside of court, legal assistants help lawyers with administrative stuff- doing legal research, organizing paperwork, etc. But the lawyer holds the sole responsibility to the court.
Unless DoNotPay has a strategy to change the law, they are in trouble. It seems that this case was a publicity stunt and not part of a larger strategy.
It's sort of a catch-22, Law in the US is only a lucrative market to disrupt because the regulation and gatekeeping has made labor expensive. If lawyers didn't bill 300+/hr in the US, then an AI powered startup to replace them wouldn't be cost effective. There's a joke I saw recently about a guy hiring a lawyer for a $800 traffic violation and getting a bill for $1200.
I can't speak to the price of a lawyer abroad, but a quick google seems to indicate US lawyer salaries on avg are up to ~2x as much as in some parts of Europe[1][2].
Unless DoNotPay has a strategy to change the law, they are in trouble. It seems that this case was a publicity stunt and not part of a larger strategy.