TLDR at the bottom 

I've worked in many different environments and I'm an ex-smoker
In my experience in customer facing roles (shop floor, call centre) everyone got the same breaks. What you did in that time is your own business. Smokers did not get more breaks than non-smokers. In my first job the supervisor would set the breaks for the shifts and if the supervisor was a smoker then we would all get 2 breaks. Although even as a smoker sometimes I just couldn't be arsed and carried on working. Shifts were only 4 hours and 2 fags in that time was a bit much.
When I've worked in non customer facing roles it has been up to the management to keep an eye on productivity. In one office the smoke breaks got out of hand so they policed it a bit more.
My current work place is split with back office staff and customer facing. The customer facing staff are entitled to a 15 min break morning and afternoon. Again, what they decide to do with it is their own business. It's also possible for them to nip for a fag in between appointments providing. Non smokers also have time in between appointments and it's up to them what they do with it. But overall everyone does the same amount of work.
As a now non smoker I'm not bothered in the slightest. Everyone does the same amount of work but you do find the smokers still working gone 5:30. When I smoked I stayed behind an extra 30 Mins a day to make the time regardless of if I needed to catch up. This wasn't something which was asked of me.
As PP said, we are treated as adults to manage our own time and it's up to management to ensure no one is taking the piss. I'm sure if everyone went for smoke breaks and there was no one to cover the phones they would start policing the fag breaks a bit more.
And although smoking is an addiction it's not as black and white as it being a choice. I started smoking to look "cool" as a teenager and found it very very difficult to quit after smoking for 20+years. I found I was much more productive when I had a fag break.
TLDR: it's down to management to ensure no one is taking the piss. As long as everyone does their fair share of work I don't see the issue. And if non-smokers want/need to take an equivalent break they should be allowed to. (I was often accompanied on my fag breaks by a non smoker)