uglygun,
What you say about drivers side......passengers side makes sense to a degree, and so does referring to the bolt release and ejection port as a way to indicate sides but.......
not to be a nit-picker or anal about it..........
Much of the world drives from the right hand side of the vehicle in which case the passenger would be on the left!
and.........
your rifle method works well when referring to a standard AR-platform firearm. It comes up short when referring to a LH Rem 700, just as an example.
After 37 years in the automobile business, both on the manufacturer and dealer level, I can assure you that it is the industry standard to refer to the right or left side of a vehicle from the drivers position. No confusion this way, as it doesn't matter which side he's sitting on as long as he's facing foward! Dealing with vehicles and customers from England, Australia, and Japan will get a person into this habit quickly.
As far as firearms are concerned, after checking with several authorities, the industry standard calls the left and right side of a firearm from the firing position. Standard practice (with a few exceptions) where pins are concerned is that they install from the right and remove from the left. "Right in and left out" is what a prominent gunsmith once told me. However, as several members have posted, it's always best to check!
I don't mean to sound overbearing about this subject, but it would sure help everybody concerned if a universal standard was adopted.