Why are all iso reels left-handed reels

Generally, anglers operate their fishing reels with their right hand while holding the rod in their left hand. But nowadays, most of the wheels' cranks are interchangeable between left and right hands, as long as the nut on the other end of the crank is unscrewed, you can freely change the direction of the crank.

After a fishing trip, you need one hand to control the rod and the other hand to control the net, according to your personal habits, it doesn't matter if you control the wheel with your right or left hand, as long as it's convenient.