That assumes that this idea would actually work. I doubt that it will actually be challenging to get hold of cigarettes after this goes into place, there will almost certainly be a lot of shops that will still sell them to people who are under the minimum age. For it to work properly I think there would have to be a lot of money spent on enforcing it. Alternatively though, one could argue that even that is better than not having any measures put in place.
As a Brit this took me forever to work out lol