I would assume the _reason_ the picture is being taken is the primary driver of that bias, and in this case, they're both professional photographers with simi

I would assume the _reason_ the picture is being taken is the primary driver of that bias, and in this case, they're both professional photographers with similarly nice equipment and public portfolios that are involved in creating income for them. Plus, the picture obscures it, but you can see the waves coming for a good distance. You'd expect two drummers to be on beat without much difficulty.