ummmm ... Possibly, although
(1) that would be tempting parents to leave off any highly visible safety restraints on short journeys
(2) you would get an inconsistency of application if some forces allied the law to all minors, some only targeted booster seats, etc
(3) what's the point in making a law that applies to children up to 18 if you don't bother applying it to anyone over, say, 12?
(3) if you get married at 16 or 17, and pass your driving test at 17, would you get stopped if you smoke with your wife in the car? If not ... why not? Selective enforcement of the law is never a good thing.
(4) if you are driving a car at 17, and smoking, would you be stopped because you have got yourself in the car?
What you have to remember is that, once a law is made, thousands of people, including all criminal lawyers, will start looking for flaws, loopholes, inconsistencies with the human rights legislation, etc.
A law like this is a lovely idea ... but it will never work in practice.