You can clearly see that there are no children present from the photos.
You talk about not automatically believing me but have no problem automatically believing the goady poster who claimed "loads of parents" took their children to an adult drag show hosted by someone with the F word in their name, without a lick of proof, and without bothering to do basic fact checking?
It's very easy to look up photos from the evening performances (the ones from the Daily Mail were from much earlier in the day), or look up the layout of the event and the sightlines of the stage.
The stage does not face the river path and the photos show that there was a crowd in front of the stage. Fairly logical then that passers by who were outside of the audience area (so looking at the stage from right angles and through the crowd) would not easily be able to see the stage. Just common sense.
In terms of sound, obviously you can hear the music as music carries. Able to clearly hear individual lines of dialogue from a distance? Hmmm.
For anyone who hasn't been there themselves, the reason I am sceptical of the poster's claim is because it's a busy and noisy area with lots of competing noise. There's an outdoor bar right around the corner playing music through loudspeakers, plus a busy food market with hundreds of people eating dinner and drinking basically next to it, plus hundreds of people milling on the terrace directly above preparing to go in to watch one of the two plays start. That's a lot of ambient noise and other music and other speaker systems, for vocal speech to be competing against. I could easily hear the music and general roar of the crowd from some distance away, but struggled to make out individual dialogue even when I was right in front of the stage, because there was so much competing noise.
That is why I don't believe that person.