Why is the kicker motor usually mounted on the passenger side and the vantage on the right side?

A few things I've picked up from conversations related to this....

Some boats tend to list (lean) when fishing alone (wheel boat, side counsel starboard adn some smaller tillers) so placement of the kicker port side balances this so then the Vantage ends up starboard.

A lot of it boils down to personal preference and for those with tiller handled kickers it's which arm they like to control the kicker with and in rare instances where they have a graph placed to watch their trails/routes/gps/sonar/etc. For guys that steer from the wheel the listing issue might be more important so boat control comes effortless. Obviously your graphs are right there when sitting in the big boy seat.

The best thing you can do, if at all possible, is fish out of boats (of similar brand/model is best) with the setup you think you want. That will help make your decision and the odds it's a flop are greatly reduced.

And there's probably another 400 reasons I'm sure others will share. I'm off to the mighty Miss hog hunting.... Hope these hurricane like winds of late subside.