One other thought:
Yes, in 3E / 3.5, everyone has "levels", including the NPC classes (commoner, expert, etc.) But, that doesn't mean everyone is high-level. You still need 1000xp to make 2nd level, 3000xp to make 3rd, etc. IMO, farming isn't going to earn you many XPs, nor is everyday blacksmithing, so those "experienced" farmers and blacksmith are still not going to be very high-level, and still aren't going to be very good in a fight. A commoner is fairly comparable to a wizard in a fight (d4 hit dice, wizard BAB progression, no armor proficiency, proficient in one simple weapon), and an expert is fairly comparable to a rogue in a fight (d6 hit dice, rogue BAB, light armor, no shield, simple weapons) -- but without any of those PC classes' spells or special abilities that make them actually *capable* in a fight.
Even though they have "levels", they sure aren't adventurers.