Consider the following data - feel free to play around with the SQL queries yourself (Links at the bottom)

    Average number of ______ by site

                        upvotes/question    upvotes/user        answers/question        answers/user
    Unix&Linux          8.71                5.19                3.05                    1.81
    Stackoverflow       6.38                12.76               3.17                    6.34
    AskUbuntu           6.34                3.93                2.61                    1.62
    Linguistics         8.74                4.74                3.25                    1.76
    Superuser           6.45                4.47                2.98                    2.06

My reading of the story is not upvotes in general, more like upvotes in the context of the overall userbase. Fewer of us answer fewer questions than any of the other 4 communities I picked on a whim. Not only that, but we seem to reward questions less than the other communities. If I was to make a rash judgement, I'd say we prefer to just harvest what the community has to offer but feel less inclined to contribute and to reward those who contributed.

https://data.stackexchange.com/superuser/query/614178/answers-per-user
https://data.stackexchange.com/superuser/query/614175/answers-per-question
https://data.stackexchange.com/superuser/query/614068/upvotes-per-user
https://data.stackexchange.com/superuser/query/613862/number-of-upvotes-per-post

PS: I am tempted to make a few more queries - if you have one in mind, let us know in the comments and I'll see to it that I find the time to run the best ones as an update to this.