I see probably an average of a half dozen questions a day on meta (fewer on weekends obviously) that the OP clearly meant to ask on the main site.
For users with a low rep here, when they start asking a question, can we provide a more obvious hint than the box to the right of the question that we all see? A popup that they have to dismiss that asks them if they're sure their question is about the network, and not about a coding question they have. The popup would go away potentially after they've had one or two questions with
x upvotes or after their rep has exceeded
Of course some folks won't read a big sign you smash them over the head with, but I think it will help others.
I think this could potentially reduce some of the noise here, as well as reduce the amount of work the mods have to do, without hurting the rest of us who have been here long enough to know the difference.
I will confess that I don't know what we're showing for new users today - you can't ask a question in an incognito window and I don't have a sock puppet account to test with. I'm assuming there isn't special treatment for new users, or if there is, that it isn't very effective. (Then again, what do I know, maybe 200 off-topic questions never end up getting asked here in the first place, so the problem is a lot smaller than I think.)