Yep, I agree wholeheartedly. I feel like asking if they can't afford a set of headphones.
If it was I business conversation I'd stand near by taking notes. I'm sure their company would love to know that their staff are discussing sensitive details in public. Or just record it all on my mobile and send it to their company.
I have had a discussion with someone who said what's the difference between someone talking on a video call to a mobile call or the person next to them. A mobile call you only here one side. Two people talking in a public space don't shout (well, not normally!).
Trouble is, people have gotten very comfortable with doing video calls now thanks to Covid-19. At work, hardly any did Teams calls. Now they swear by it as it saves the hassle of looking for a free meeting room. When I told one of the heads that people will be doing more of these calls from their desks - whenever we eventually go back, he was so upset at all the extra noise in the office this would cause. Given he's younger than me, he's not very adaptable. But this situation is far different to being on a plane or in the lounge, or any other public space.
Re children playing games with the sound on, I once had to endure an overnight flight with a child in the cabin playing a game nearby. Earplugs and noise cancelling headsets only seemed to block out everything else but not it!