Wow - it's about balance and the level of the distraction though, isn't it? As fanning is generally not uncommon behaviour and has been in theatres for probably 200 years, for most people and for most theatres, it simply isn't a distraction in the way that someone using their mobile phone is. I'm not denying that for some people, it can be a distraction, but it's managing reasonable expectations. If this were 1894 when almost all theatres were still lit by gas, almost everyone would be fanning because of the heat generated.
I mean, you could be 5ft tall and the chap in front of you be 6ft 3 and as a result you can't see a lot of the performance. The show is sold out and there is nowhere else to move you. Do you expect the theatre to remove the person who is too tall because they have ruined your experience? Should the theatre ask people their height when they make a booking? Should you be entitled to your money back? Of course not.
I'm afraid It's a public building and it is always possible than one person out of 200 may be distracted by someone doing something - that just has to be accepted. If behaviour in unreasonable, then staff will do something, but, as a rule of thumb, a fan in a hot theatre is not generally regarded as unreasonable by most if not all theatre managements and most, I suspect, regular audience members.
Of course if the production is really good, it should take more than a bit of fanning two rows away to distract you from the drama! 