UK Workman on Tin Man

[Captain]

My guess is that the costume designer chose for them to wear kilts and then had a conversation with the producer and/or director something like this:

Costume Designer: "So I've got this great idea for the resistence movement's costumes... Here's a drawing... They'll wear these great, tough-looking, solid-color kilts..."

Suit: "Won't people think they're Irish or Scottish or something like that?"

CD: "Ummm... no, it's not a wool, tartan kilt. Trust me, it'll make them look great, plus they'll stand out."

Suit: "I don't know, I'm pretty sure people will either think they're from England somewhere or that they're cross dressing."

CD: [exasperated sigh] "Whatever. Would it help if they wore pants under them?"

Suit: "Perfect! I love that idea."

CD: [under her breath]: "Moron."

At least I like to think that's what happened.

[Wompet]

Or, if it was filmed in New Zealand, there is an XMarker down there known to have worn green tights with a kilt. Maybe the costume designer saw that, and it was burned into her brain ...