Hey - I'm really not sure about all these "Left -handers don't have any more problems than right-handers" comments.
I am left-handed and a teacher.
Some left-handers do seem to manage with little or no problems. You maybe lucky to be/have a child who is one of those. Even in these instances I think that probably they are having to work/concentrate harder than right-handers when using right handed tools - it is just that not having used a left-handed version they don't realise how much more natural it can be. ( I base this on my own experience of not thinking about it much until I tried an equivalent left-handed tool ( eg scissors, serrated knives) and realised how much easier it was to use the left-handed version and how much less physically tense I was too. Also, left-handers have more tool related accidents in the workplace than right-handers - are they innately more clumsy or is it because the tools have been designed for right handed use?)
My experience growing-up was the opposite of Talkingpeace2's. I wouild have welcomed more help and understanding from my right-handed teachers that I was experiencing as a left-hander
While some left-handers don't experience problems, it is true that some (even many) left-handers will have the types of problem the op was describing such as bumping elbows ( because of sitting on LHS of a pair) and smudging work. Some left-handers may automatically find a good paper position for writing but others will need to be shown and taught. Why is this so controversial? Why shouldn't teachers be aware of this and take steps to help. Riversidemum outlines many of the things teachers need to do/be aware of.
Just because a particular right-handed child has more co-ordination or handwriting problems than a particular left-handed child, it doesn't negate the fact that there are common issues experienced by many left-handed writers.
I totally disagree that it is "only an issue if you make it one." If your left-hander is bumping elbows and smudging work then it is already an issue!
It can also be an issue when teaching hand-work like sewing, knitting, use of tools etc. It is often easier when a right-hander is teaching a left-hander (or vice versa) for the learner to sit exactly opposite the demonstrator/teacher and do things as a mirror image. For this purpose ,sitting the left-handers together would be helpful and it is this kind of situation I think the OP was referring to.
You don't need to "pair up" LH and RH children for writing, just make sure that when a left-hander and right-hander sit together, the left-hander sits on the right side of the pair. Two left-handers or two right-handers sitting together is fine!
I don't see the OP as labeling her child as disabled or making a problem over nothing, just asking for advice about problems that her daughter is raising.