I thought maybe there was some international aspect to this and that it might make a difference where the jacket was manufactured. But I have two foul weather jackets, two different brands, both made in China, and one has the zipper car on the left and one on the right. Another jacket is made in Portugal, and the zipper car is on the left.
Rick and I went to a local play last night, and during it one of the male characters had to put on a leather jacket. I noticed that we simultaneously leaned forward to intently observe which side the zipper car was on. I know it is ridiculous, but at least it is sharpening our powers of observation.

By the way, it was on the right.