Weellllllll...And ... we do. But you can't fix wealth gaps overnight.
From Wealth Guidelines:
Italics are mine.The primary goal is to establish the connection between experience and wealth will best maintain folks near the average wealth target. These tables are not meant to defy common sense – a session spent hunting rabid wolves is not likely to produce significant monetary gain, for example. As an alternative, XP can be “banked” towards larger rewards, typically middle- or end-of-plot rewards.
Veilan will probably sharp shoot me on this (cause he's a MAD GERMAN SNIPER!) but:
If a PC is significantly low on wealth, one might assume then that he hasn't been awarded wealth rewards based on XP gains (as our standards direct). Therefore, we can take the step of saying, "Well, all of that XP is being "banked" towards a larger reward."
That larger reward may be a nice piece of jayde13wt™ or it could be a cache of potions or a big chest full of gold...
Simply run an appropriate encounter (like, not wolves) and then drop down a large reward.
"Oh, check it out, these bandits were doing really well for themselves, they have all these gems, coins, and magic potions that they have been stealing from caravans."
I mean, yes, we're not going to take a 10th level character at the extreme low end and bump him up to average in a single session, but if you've a mind to do so, you can get them into the ballpark rather quickly (relative to the pace of their prior reward gains).
I assure you that no one is gonna bitch that it didn't happen 'overnight'. They're going to be stoked that they are making progress at all.
EDIT: The other assumption is that all of their awards have been in the form of consumables and they used them all. I don't feel that there is an appropriate response to that in our wealth standards other than the 'adjustment' factor. I think we can still assume "Banked XP". So long as we are bringing PCs up to 'average' without bringing them over, it all comes out in the wash.