Why can they only fix near or distant vision?

I posted a similar query a few weeks ago asking if anyone had had cataract ops for close vision but I didn't receive any replies from anyone that had actually had this done so I was very interested to read your post.  I feel as if this is the best option for me as I'm slightly disabled so I'm indoors more than out and about so my "sphere" is fairly close ie for reading, iPhone, make-up. Because of being in a lot of pain I don't sleep well and look pretty awful most of the time and therefore being able to do my make-up particularly eye-make-up is very imprtant to me, as well as being able to see my iPhone. If I had to put on glasses every time my phone pings it would drive me mad! However I'm very shaky about this decision as I don't know anyone else who has had it done for close vision -    everyone else has it done for distance. Like you I can see fairly well close up for reading, seeing my iPhone, and make-up. Food prep is slightly blurry because the distance is about 20-24 ins which is a bit further away.  Having had them done "close"  can you see to do your make-up, particularly your eye-make-up clearly? Do you need a magnifying mirror for that? (If you don't wear eye makeup can you tell me if you could though). Also can you see to do food prep, see your iPhone, read, without putting on your varifocals? I've got varifocals and was told they wouldn't be right after the op so the fact that yours are still ok is interesting, Do you know what strength lens you had? Mine are to be -2.5 (I think that's right) with a Toric in my right eye to correct astigmatism and an ordinary lens in the left. The surgeon proposes to do one close and one what he calls close-and-a-bit and from what I understand I'll be able to see clearly from about 10ins away to about 3ft 6" away clearly. Closer is likely to be a bit blurred so I'd need to use a magnifying mirror but he says it won't be blurred, and that I'll be able to see fine just for being in and around the house and for cooking.  I would be so grateful for a detailed reply angieth and many thanks in advance. If anyone else has had them done for close vision do please respond. Thank you. 

My dad had his done for close vision. His rationale is that he is older and spends more time indoors reading and watching tv. Putting on glasses every time he needs close vision also means keeping them on hand. His vision was never very bad, even in his 80's. Since his surgery about 3 yrs ago, he uses glasses when he drives. He finds it easier to leave glasses in his car than to carrry them around for near vision. He is still happy with his choice. The choice is so individual though,depending on lifestyle and correction available for your eyes.