Yes, all of these reasons.
I think there's a few reasons it's seen less in LL:
1. Less check swings in general
2. Often there is only one umpire
3. If there are two umpires, they are usually kids
4. Manager/ coach don't know you can appeal
5. And the most obvious answer, because they just don't care. Unless it's an All Star game, I'm not asking for an appeal.
I see a lot fewer borderline check swings in LL.
Kids often are not strong enough to really check a swing.