I believe the WoL numbers that Allie used up there are effective heals. Recount also does this natively, when you look at the healing meters, they produce effective heals, not total heals (which would include overhealing).

I hear what you are saying though. Another difference in healing is raid healing versus tank healing. Generally speaking, raid healers are going to have higher HPS than tank healers. I would gander that the pallies topping those meters are getting a lot of use out of Light of Dawn and Holy Radiance. Let me go check those logs a sec...

And indeed, virtually all of the paladins that I sampled on those top 10 leaderboards had Holy Radiance as their top healing spell. So there you go. If shaman are being used as tank healers more than raid healers, you aren't going to see them on those top 10s as much. In fact I see healing rain as the top spell for virtually all the shaman on that healing list too.

Anyway that would explain it. I don't know which classes make the best tank healers (I don't heal, ever), but I do know a bit about the mechanics of throughput and HPS, and AOE healing, similar to AOE dps, is always going to be higher than single-target, generally speaking.

For most of the fights right now my Healing Rain is on constant cooldown. Yes, and I think my highest healing spell is chain heal because we're on 10 man 2/8 Working towards downing Zon'ozz. Firelands I spent a lot of time being a tank heals, but in Dragon Soul I spend most of my time trying desperately to keep everyone alive, not just the tanks. So much AOE damage...

Overhealing doesn't matter if you have pretty close to an infinite mana supply. Shaman care, Paladins don't.

Shaman have to play conservative, still. Paladins, even with the judgement nerf, are still able to use enough mana CDs to not care. Shaman are still stuck with HORRIBLE mana return mechanics. Water Shield drops when you can't afford to put it back up, or if you do you lose a GCD. Mana Tide helps that Holydin too. And the Holydin can autoattack if they are low on mana, the shaman has to cast LB during lapse moments. That Holydin in those same moments is hitting Divine Plea and getting their blue bar up near the top.

I think the defacto 'Holy Radiance + Light of Dawn, Lol top meters' is a bit unfair.

When you consider all the fights in DS, think about it logically.

Morchok - Tank damage can be equal to melee damage, AoE hitting Melee + tank viable to tank heal
Zanozz - Group up phase all healers AoE heal.
Yorshaj - Many times where AoE healing when everyone is packed can keep tank up as well.
Hagara - Tank healer basically gets most of the healable damage, and if the tank is good he can assist even with raid damage
Ultraxion - Constant AoE, even the 'tank healer' can become an AoE machine. Later half of the fight, so much AoE healing is present tank-healing paladin can just AoE heal. (Hence pallies scream bloody murder if they don't get blue)
Blackhorn - Lot of times you stack up to heal, tank damage only picks up at end of fight.
Spine and Madness - Definately more raid-heal heavy.

As you can see, these days, just saying 'I'm a tank healer' isn't what it used to be in wrath. In wrath, you healed the tank and yourself and didn't stop. Now, you are expected to pitch in for AoE. That's why a lot of guilds are 2-healing most of DS, is because so many classes can actually succeed at both. The world of cut and dry tank/raid healing has been gone for a while now. Many fights leading up to now were the same, It's just that now paladins were given AoE tools to handle them bringing them up to that level.

Personally, I believe some of the gap between healers is still skill based. Paladin healers have always had to force themselves to be very mana aware ('infinite' is a generalization. That blue bar does move, and somtimes like a see-saw where missing one swing and you're done. It's a rhythm). They also are generally the largest subscriber to the ABC's of healing. (Always Be Casting) Alternately, shaman has been changed every patch or so, priests have two healing specs. It's no wonder that the two classes that have had the least impacting changes, therefore most practice at what they do, are towards the top.

tl:dr Holy Paladins have an easier time at the top because of few changes and a spell they can treat exactly like divine light, making life easy since they have not changed tons.

Trust me.

As an ex-holy paladin, if I am being relied upon to heal the tank, my numbers will be lower. The healing meters are pretty much useless to me right now, and might as well be renamed the "how many times was I able to cast holy radiance" bars.

I agree that paladin aoe was kinda gimped before this, but I don't like this solution very much. It makes me feel like there's no real strategy involved :(