America, I don't get it: Units

I am an engineer, and units are very important to me. Probably the only thing that all my professors agreed on was how important units are. My brain is programmed to understand SI units, and I thought I am smart enough to be able to train my brain to switch between unit systems. Well, I failed at doing that. I can tell that +90F means it is hot, +70 miles means a speed ticket is on the way, and that a gallon of milk is a lot for me to consume, but that is about it. I tried, I googled conversions, I thought about sticking conversion tables on my fridge so that I can see it everyday, but I am a lost cause. To be honest, I am frustrated with the unit system, and it doesn’t make sense to me. Like why America you have to have a system that is different from the whole world? I thought you will change your mind after the challenger incident, but no! On the note of units, paper sizes have the same problem. A4 didn’t do anything wrong to be replaced by its shorter and wider rivalry the letter size. When I print stuff, they don’t look ‘right’ to me, plus they don’t fit in any of the folders that I own. My bigger problem that now I need to redesign my resume to make it fit the letter size. I am just putting this idea out there, if you ever switch to SI units, please switch to A4 while at it.