What do you mean by 'the southern hemisphere teams seem to have had a big advantage in the junior grades since forever' ?

If you look at http://cmasuwhc.org.au/CMAS%20WTD2/HTML/Results2.htm the results for the juniors don't really suggest what your saying. Looks pretty evenly matched to me

I totally agree that the quality of the championships the juniors have doesn't seem satisfactory with the large amounts of money they have to spend to attend but surely we should be wanting to increase the number of countries entering junior team to the world championships rather than watching those teams that do already enter pull out.