Oh dear. Some people need to grow up a bit.
Smoking is banned in workplaces in Scotland. Performers on stage are at work and therefore may not smoke.
It is an offence to smoke and also to permit smoking, so it's not just them who could be fined - it's the venue, the stage crew, the audience...
I think this is a good law. I also think that the comedian in the article who says he can't perform well without a cigarette has a problem.