And yet the farmer, who has dedicated years to farming, isn't even a very good farmer.
BTW, the wizard never gained any experience, ever. He was given it, because there is no mechanism for NPCs to gain experience.
Most people are at the level they are at because they progress up to their level of incompetence . . . wait, this sounds awfully familiar . . . .
For elves, I don't remember where it came from, but one of the ways we have handled it was that they age physically fairly similarly to humans, but they're expected to stay in their communities, doing a few things in the 90 or so years before maturity. Primarily, this includes learning about whatever they want and partying so hard over the course of 90 years that they take a penalty to con. By the time they reach 110, they're done partying, they have learned a bit of this and that, and are ready to be productive members of society.
The feat Breadth of Experience could also be used as an indicator of relative experience, because you can take it at level 1 as an elf, implying that they have been going out and doing/ learning things for a very long time.
This is an interesting discussion, and one that I've chatted about with people in the past. There's a couple of points I think might be interesting to consider.
The age chart is poorly defined. Humans are not adults at 15. That's utter crap. Sure we reach sexual maturity somewhere in that vicinity (I personally grew 6 inches and put on ~60lbs in my 16th year), but sexual maturity and emotional maturity are not equivalent. The prefrontal cortex, the part of the human brain associated with what we would normally call "maturity," doesn't complete growth until around age 27. So there's a basic problem of what do we mean by maturity/adulthood? Are we saying that elves grow more slowly than humans, or that they reach sexual maturity later, or that they reach emotional maturity later? (Here I'm using elves to represent the long lived species). Do these species have the same stages of growth as humans do? Chimps don't. They reach brain and sexual maturity at roughly age 13 (which looks a lot like the orc pattern. Actually, a lot of orc stuff is very reminiscent of chimp society). Chimps don't have that "teen-ager" phase that humans do, where we are more or less physically mature, but not fully formed emotionally. I've seen this used to explain elves before. Elves have a much longer "teen-age" phase, where they are simply too flighty to acquire many skills (although they do acquire some skills, such as the weapon proficiencies). It might also be the case that, while fully grown, they aren't reproductively mature yet, that their fertility doesn't mature until after 100 or so. That would be interesting to explore, but without fertility data...
But what about dwarves? They live a long time and typically aren't described as flighty? Perhaps they simply take 40 years to acquire those racial bonuses? Perhaps it's not til 40 that they can tell the males from the females? It's the genie-kin/outsider-kin that really make no sense. For some of them, they look completely human (or almost) and yet it takes 60 years to reach adulthood?! I think that'd point to something being off pretty damn quick if we were referring to physical maturation.
I think there's another possibility here as well, and it may have been the original point of the chart. Adulthood is culturally defined. These basic ages are meant to be "the age at which members of community X allow their young to go off alone." From that perspective, elves (and other long lived races) do reach physical maturity on a commensurate time line, but take a long time before they're considered full adults. Elves simply see everyone as children before they've got a good century under their belt and DON'T LET their "young" go off on their own. In that case, elves or ifrits or whatever that are raised among communities of different races (like humans) WOULD be considered adults at the same age as everyone else. If that were the case, then an elf raised among humans would be considered an adult at 15 (or so) and off on their own. Since they were raised among a different community, they would loose those racial benefits/bonuses that we see them normally acquiring (things that their normal community would consider essential before letting anyone off on their own).
Of course, I've also had discussions with people arguing that the cause of the extended life spans has to do with magic affecting the rate at which telomeres decay... at which point I like to mention that these are fictional species.
These two are related, I think. In a lot of historic cultures, humans were considered adults at 15, or even younger. If wasn't uncommon, especially for women, to be considered adults as soon as they were sexually mature (men sometimes had to go learn a trade first, so that they could support a family, which began a cultural pattern of men marrying younger women that some cultures preserve pretty rigidly even today). It could well be that Elves spend decades learning to used their racial weaponry, honing their eyesight, developing resistance to enchantment spells, etc., before they're culturally considered to be adults, even if they're sexually or even emotionally mature by 30-50, say.
In my games, all the races that live longer than humans develop at about the same rate, then the 'immortality factor' kicks in. So, if a human hits puberty at about 13, a dwarf hits it at 15, an elf at 17, give or take.
It always bugged me that an elf with five times as much life experience as a human was no more skilled or capable than that human.