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Because it involves technical stuff that generally is percieved as boy toys.
Simple analogy "few" years back during the masters time, we had around 303 colleagues on the year of which 3 were girls... There was no selection like boys only...
Same here flying is one part taking stuffapart is other side of the hobby.
As ive taken a number of girls on a short ride, none of them wanted to know more - ok i get it im not marlon brando, but still... Moving pictures good try it meh...
Ive had my wife flying zmr long time ago in angle ... As long as i was staring like hypnoyized she flew, landed and passed the tx "have fun"
Ive bought a nano to my niece as she was fascinated by quads... 2 weeks later imet her again, have you flown? Once then it had to berecharged and iforgot - ergo moved to something else..
And then we have a foum like here - friendly inclusive without stupid questions stil i think ratio is like 98-99%
Just to be fair bycar mechanic is a girl an shecan't belive i only know where the diesel and wipers fluid is going