While it is true that they usually like dark, private places - it would seem your girls are showing they are comfortable with a more open and light area for laying. I would suggest maybe putting a rubbermaid nest box with no lid on it out there for them to get used to going "in" to somewhere through a door similar to that on your lovely boxes....having the lid off will give the box a more open and inviting (to them) feel.
It also looks like your girls enjoy each other's company while preparing to lay - perhaps you can open up things a little so that they can have the option of a communal box *or* a private box?
Or, if you have the time, I would suggest sitting out in the coop with them during their normal laying hours - as you see them starting to nest down in the roost area in preparation for laying, pick them up quietly and calmly and place them in the nest box. If they are truly in the mindset of laying they will generally just settle down in the suggested area and carry on with their mission. It may take a few days of this before they start going in on their own when they feel the urge to lay, it's all about building the habit and association you want for them - urge to lay = go int the box.
I recently had two start laying and they wanted to be floor layers not nesters. After over a week it was clear they were not going to change their minds on their own. I used the quietly move them method - one took only one move/day and the other took two moves/days -- now they both just hop up in the nest, do their thing and go on about their day. I just waited quietly while they went through their "nest" search all over the coop floor, they finally picked their spot and settled in with "the look" of a hen waiting on her egg and once they were clearly in the right state of mind I simply moved over quietly , picked them up carefully and placed them in a nest box. Neither of these are my friendliest birds, to say the least, and are quite flighty under normal circumstances, but a hen ready to lay is in a different state of mind and neither of them put up any bit of a fuss about it at all.