How rare are IPS screens?

I know its extremely hard to tell because even nintendo didnt say shit about it. Im just curious. I always found that my top screen had better colors than the bottom one, but I thought it was ok because i didnt know there were more than 1 type of screen. Yesterday while looking for 3ds stuff I learned that there are 3ds with TN, IPS screens or even both. Downloaded 3dsident and I confirmed that my top screen was in fact a IPS. Its a common new 3ds xl red that i bought 2nd hand so I was happy.

But I still find super weird how there are 2 types of screen.