Do manufatures ever try stuff for fit

In the last week I have installed some metal A arm guards , front and rear and a metal gas tank protector. It was amazing how crappy they fit , had to drill holes for both the rear A arms and the tank protector and the rear A arm guards were a bit to wide and were squished when I tighten them up. Maybe the fit has changed over the years but if so the manufacturer should keep up an this
Hal