The only thing that is genuinely weird is having four different certificate stores on a system, each with different trusted roots, because the cabals of man-children that control the WebPKI can't set aside their petty disagreements and reach consensus on anything.
Which makes sense, because that would require them all to relinquish some power to their little corner of the Internet, which they are all unwilling to do.
This fuckery started with Google, dissatisfied with not having total control over the entire Internet, deciding they're going to rewrite the book for certificate trust in Chrome only (turns out after having captured the majority browser market share and having a de-facto monopoly, you can do whatever you want).
I don't blame Mozilla having their own roots because that is probably just incompetence on their part. It's more likely they traded figuring out interfacing with OS crypto APIs for upkeep on 30 year old Netscape cruft. Anyone who has had to maintain large scale deployments of Firefox understands this lament and knows what a pain in the ass it is.