booster seats

So that new Ontario law tells us that for a person to go from a booster to a normal seat in a car the person must meet the following;

80lb and 4 feet 11 inches.

Now my daughter has a goal in mind.

My questions is. Does this rule apply to only children or adults as well? I would think that there would be advantages for anybody who is not almost 5 feet tall to be a booster seat. There are some adults who could make great use of a booster as they are too short for the cars which are built for the typical Anglo driver here in Canada and the USA for that matter. How many times have you been driving and seen a headless driver? Also doesn't an air bag work best if the person is over 100lb? Its why children are not allowed in the front seat of a car until they reach that weight.

So I think that the rule should apply to any person and not just a child.