Bicycles predate motorcycles by a long while... and the reasoning is so that you can do hand signalling with the hand opposite to the side where you drive.

I used to live in the top of a steep af slope, so I always brake test before, several of my neighbours have been in accidents cos of brake issues during rainy or cold days.

On my bicycle I always drove with rear always pulled all the way and even then it was kinda like "Jezus, don't let me die, pls!"