A score of 140 to 180 out of 200 isn't exactly shabby for a new shooter. Join a shooting club though. You'll get lots of help, meet some great people and have fun shooting. However, the fit of a pistol is essential. If you can't easily reach the trigger with the trigger between the pad and first knuckle of your finger, the pistol is too big. Changing grips can sometimes fix it. Mind you, I find stock Glock grip slippery. Again, easily fixed with a slip on rubber adaptor from Pachmayr.
Any job that requires you to carry a firearm should also send you for training. If they don't, look elsewhere for work.
"...I dont understand why..." Logic doesn't apply to firearms laws. Anywhere.