Earlier quoted context omitted.
It's hard to say if a 5 year old is a boy or girl withought clothing identifiers so it's not always obvious. However, from a practical standpoint a dress takes less effort to make, you don't outgrow them as fast, and it makes changing faster so I can see why it would be the gender neutral choice.
As a Father of four, this makes a whole lot of sense to me. I'd guess they'd potty train faster in a dress than in pants.
Living in a climate that is warm to hot most of the year, little kids basically just need a nappy and a tshirt or singlet around the house. It looks very ghetto but it is practical and not unlike wearing a dress I guess.
Chucking shorts on over the nappy to dress up for a public outing doesn't seem to alter the complexity of things appreciably. Little boy fire engines take great pride in being accessorised with a fire hose and whipping it out never seems to present any challenges or inhibitions to them. At least compared with aiming it. Perhaps we should paint a fly in the toilet bowl.