So, if I've got this right, we can't call inanimate things 'he' because that's sexist (see the other thread) and we can't call them 'she' becasue that's sexist. It seems to me that some people have a remarkable capacity for outrage.
And as someone who sails I have just had a little snigger at the idea that men call boats she because they 'own and control' the boat. More likely they call the boat she because they are/ were well aware the boat owns and controls them .
but boats are referred to as being female, aren't they ? Where on earth do you get the idea that "nobody does this any more", OP?
As for cars and other things - I have had male and female cars (the ones with enough character to have names) and my DC have a great and glorious mixture of boys and girls amongst their cuddly animals. I would definitely describe myself as a feminist and I really don't see the problem.
I call steam engines "he", and often refer to animals as "he" - the squirrel that comes into our garden, a dumb butterfly that came in and got stuck the other day. If you attribute a personality to something, then you tend to refer to it as he/she because "it" is not personal enough.
That doesn't make it sexist, just anthropomorphic.
Oh and "Mummy and Daddy" is a cultural thing, not necessarily about age - in some areas/classes that's just the normal thing to call your parents. No point getting angry about it, she's not being infantile.