But we non-PAL holders are not testing the gun (ie firing it), we are merely holding the gun, see if we like the feel of the gun, and see if we can carry it and not get tired.
Since you are using car as an analogy, the policy of not allowing non-Pal holder handle guns would be like a person without a license (ex: someone studying for their written test) going to a car showroom and the sales person is like, "sorry sir/ ma'am, since you don't have a licence, I will not allow you to go into the car or touch the car. However, if you will stand two feet back, I will show you all the features of this vehicle and describe how it feels to sit in the vehicle."