Your use of "bloke" implies you're in the UK, so perhaps it's just manners... But as someone who has worked in a large, multi-cultural office in the US, it is definitely a cultural thing. There are some people that have no problem chatting on the phone at full volume, in an echo-y stall, while audibly shitting. And I mean audibly lol.
I have had one experience where I was sitting in the middle stall, of three, between two people who were having a full-on conversation back and forth over me. I kept like clearing my throat just in case maybe they didn't realize someone was there... Nope, they just didn't care lol.
Just the thought of behaving like that is mortifying to me lol, especially in an office where I have to then interact with those people...
There are some people that have no problem chatting on the phone at full volume, in an echo-y stall, while audibly shitting. And I mean audibly lol.
I experienced that in New Jersey once. A man was speaking Spanish, presumably while on the phone. And he was very audibly taking a shit. He even continued talking while straining to push the poop out.
I've talked on the shitter. I heard someone dying and asked if they needed help, they never replied, just did up their belt and fled in panic. Never again!
A few months ago I went to a steakhouse with some friends and learned that 3 ladies from the wedding party in the party room had had too much to drink and were sharing a stall (small bathroom with only 2 stalls) puking their guts out for a solid 20 minutes straight. As we paid and left we saw the paramedics arrive to escort the ladies off of the premises and an employee poised and ready with cleaning supplies to begin cleaning up the wreckage their stomachs had wrought upon the porcelain.
I've been in men's room recently that didn't have urinals in view when I walked in. Which did give me a slight panic for a moment that I had walked into the wrong door.
I opened the first stall door, and there was the urinal. Interesting.
They had also adopted the European style of floor to ceiling stalls and stall doors. It was actually a very nice experience.