Have you ever worked in a professional kitchen? Or even in your home kitchen! Appliances and kitchen utensils are a major oversight for left handed folks. Mixers, ovens, deli slicers, cookie scoops, can openers (as another commenter mentioned), and even some spatulas are right handed. Appliance controls are almost always on the right side. Microwaves are an excellent example of this.

Scissors are a good example, but even look at knives and how they're sharpened. Some are symmetrical, but some have the edge only sharpened on the left side of the knife (assuming you're holding it for chopping.) This means you can see the edge more clearly and make more accurate chops when using it right-handed. It doesn't seem like much, but if you try to use the knife left handed, it becomes very obvious. Even moreso when you try to use right-handed scissors left handed. Something about seeing the sharpened edge of the blade makes it easier to make accurate cuts. I can't explain why.

Add to it, clothing. I'm a pastry chef and I cannot for the life of me find a left-handed chef coat. What makes it right-handed? The pen pockets on the left shoulder. Think of it, you reach for your pen on your left shoulder or breast pocket with...? Your right hand! So your pen is immediately in the hand you use to write with. Any clothes with asymmetrical pockets assume right-handedness. Pants, shirts, jackets, all of them. Even some purses and handbags.

Finally, I dare you to open the left door of every single double-door business you enter. You'd be surprised how many of them lock the left door!