My most uncomfortable moment on Ukulele Underground was when I posted about my own changes in teaching, allowing left-handed players to play left-handed. It was a shocking moment of anger and negativity on UU that I seldom see--so I can acknowledge the feelings that are involved.
In classical music, we don't make left-handed instruments available for students, period. There might be special cases, but I know that schools are not providing for them.
It is pretty clear that 99% of all ukuleles are set-up right handed. It's pretty clear that 99.5% of the playing charts are right handed. 99.9% of instructional videos are right handed.
So when I started teaching ukulele, with the intent of giving students a skill they could use the rest of their lives, I felt it was in their best interest to teach them how to play right handed. It seemed to be a benefit to them that their dominant hand would be fretting. It was all with good intent.
Two years later, I was teaching a class to my fellow teachers, and one of my colleagues, an art teacher (fellow arts teacher) was missing the tip of her right index finger (accident), so she had taught herself to be left handed. I saw that, and something snapped, and I immediately restrung a ukulele for her, and then started giving my left handed students (and their parents) an option to choose. I also had a few right handed students who tried to play lefty (not very successfully).
Then I came across this video of Autumn Best, and it changed my instruction forever:
So now, I give students and their parents three choices:
1) Learn righty
2) Learn lefty
3) Play lefty on righty
What's funny is that on the ukulele education forums I'm involved with, I've been yelled at for allowing students to choose (the overall mentality is: play right handed). So I can't win!
It's ukulele. Do what works for you...or for your student.
P.S. Most ukuleles can flip strings to lefty without any modification whatsoever; some companies (like Outdoor Ukulele) will ship left-handed if requested, and I tried to have about 10% of our ukuleles be left-handed (fits the population spread pretty accurately).