Hmm ... that has not been my experience.
>it's impossible to find the midpoint, because everyone has a different lived experience
Yes! That's the answer to your question.
https://www.weather.gov/fsd/twilight
It's based on how many degrees the sun is below the horizon.
I can tell you for sure nobody will say "it's nighttime" during civil twilight.
Nautical twilight maybe like 50/50 ... but again "when does the night starts?" still applies.
Hmm ... that has not been my experience.
>it's impossible to find the midpoint, because everyone has a different lived experience
Yes! That's the answer to your question.