You need to get over that imaginary image that everyone wanting to spend 150 euros on wow my friend. I didn't say average item lvl of Lord and Icecrown is the same, that's rubbish. You'd have a hard time finding an icecrown player under 6k gs unless he just dinged in the last 2 weeks. Farming gear is easy, no need to donate. Getting BIS there takes way less time than Lordaeron, that's why Lordaeron is the "hardcore realm" where people work for their **** on harder raids.
People get Shadowmourne by normal means if they have some patience and raid.
You fail to see that that's why wow always needed expansions, the game wasn't meannt to last this long in one xpac. Shadowmourne wasn't meant to be had by large numbers, but since these realms are Wrath it will happen eventually. Lordaeron will have more and more, Icecrown already has plenty.
So get used to it and maybe learn to play around it because the lolmourne is not going anywhere anytime soon, it only increases.
And even with all that there are BIS players on Lordaeron and there are Shadowmourne players on Lordaeron, it just takes much much longer.
So if you want a bite of that just play and eventually you'll have it. If you're a non smourne class you have no other option than to play around it and adapt because again, it will get more and more common.