So here's the thing: how Meta here works is different to how it works on SE. Meta sites on SE are technically their own instances of the Q&A software, another site if you will, that just happens to be linked to the main site by that main-meta relationship. This means they're completely distinct: everything is in separate databases, and very little is shared between the two.
Here, it's all one - both main and meta are part of the same Q&A instance. That means that a question on main and a question on meta are also exactly the same; the meta question simply has an
is_meta = true attribute set.
This is the reason for a number of differences to SE - I won't call them issues, because it was a conscious design decision, but it's not the same as we're used to from SE. It's the reason that meta posts earn rep, and it's the reason that tags are shared between both.
This is not to say that these things can't be worked around - I can make some changes to bring things closer to how they work on SE, if that's what's wanted - meta posts could be exempted from earning rep, tags could be separated in the same sort of way posts are. I'll add the tag separation to the TODO list for 2020.
Tag wikis technically already exist. They're not exposed anywhere in the UI yet, but they are a thing in the software, which means that adding them in as a full feature is not a difficult thing to do. Again, I'll put it on the 2020 list.