Girls are 'allowed' to be 'scared', and often get positive attention for being so. Boys on the other hand tend to be jollied out of it. you see this with primary-aged children. A group of the girls will squeal and say, totally unconvincingly, 'Oooh, I'm SOOO scared of XYZ' and back theatrically up against a wall. Unless someone steps in fast and says, 'Do you REALLY think that's going to hurt you?' other girls will join them.
The boys OTOH take the piss out of each other for being scared, and also get much more of the 'Come on Tommy! Look, it's only a model!' attitude.
As for the outdoors, girls clothes are often less convenient for outdoor play, and also show the dirt much more (white socks for the girls at primary school, grey for the boys, for example). A lot of parents still put quite a premium on their girls looking girly and neat and clean.
There is still a huge amount of ingrained sexism, and it's so common and expected that it's not even commented upon. I used to work in a school where the children in the lower years had colouring books that they could use when they'd finished their work and the teacher was happy with it. Boys got pirates/dragons/racing cars, girls got fairies/princesses/fluffy kittens. I was 😯
It's not helped by the fact that so many toys are clearly aimed at one sex or the other. It can be tricky to find something more neutral.
It annoyed the hell out of me from the time I was first pregnant back in the 90s and, um, yesterday when 2/3 of the girls I was dealing with decided something was 'scary' as the boys dashed to the front to see. I can understand that there might be inbuilt differences in attitudes towards risk ingrained from our evolutionary past, but I don't think it's right to accentuate this in a way that is likely to disadvantage girls.
ETA: Though I do agree with @Toseland about the Graun!