Question: I often see the number of votes/answers/general interest in questions on Meta Stack Overflow to be much higher in number. There isn't much doubt that the questions here are a lot more interesting and prone to debate.

But shouldn't people spend time giving answers there rather than here?

I mean, that is what is more productive, right?

Answer: 
I see two primary reasons:

1. The people that really *use* Stack Overflow, the people constantly on it (often with high rep counts) are the frequent visitors here, because they care about the site.
2. Which, combined with the fact that meta gets *far* fewer posts than SO (maybe 100 a day instead of thousands) means that each of those questions gets attention from many, if not all, of them whereas each main site question can only get attention from a few.

Thus, the view/vote counts tend to be much higher here.
There are 10million+ questions on SO and only 15thousand+ on meta.SO.

There are about 400 bounties at any give time on SO. Meta.SO doesn't have bounties but does have the "Hot meta posts" which features about 4 questions at any one time from meta.SO on meta.SO and SO. 

So as you can see, much easier for people to find one/two/three really popular meta.SO posts, since it's a much more narrow area. Whereas SO has hundreds of different areas and most people only frequent a few areas. 

So meta.SO is the only bar in town, but SO has many work places.