Why don't they just stop the import and sale of tobacco...

Theu tried that in the States with alcoholic drink, and it proved disastrous. And they are still trying to do it with Cannabis, and that's been disastrous too, even if the people in charge can't bring themselves to say so.

I suspect that if they tried Prohibition on tobacco it might well end up with it being cheaper than it is now, and as widespread as ever. Limiting the places where you can smoke tobacco, but leavinbg it up to people to smoke anywhere else seems a pretty sensible midway solution. Maybe they'll move on to a similar compromise for other things, in sensible countries.