You'll not find a bigger skeptic when it comes to non-random job drop theories than I am.
BUT, I am convinced Shop Stock is by no means completely random!
Between worlds, Town founding locations; like jobs, are located identically on the map, though
Items in their shops ARE different.
Specific shop items may appear random, but I feel that they're chosen from a larger 'Template' of
items, (Or Seeds) and not from a database of ALL the items available in the game. This spreads
the 'Special' items further out across the map, and makes them rarer.
If truly random, you would not find similar clusters of specific items. (The same sets of waist coats,
boots etc. in the same local towns) Distribution of ALL game items in all 40 'Counties' should
produce a more homogeneous distribution of 'Special' items as well. You DO NOT see this. Some
'Special' items appear to be found in largely spaced 'clusters'. (Which themselves could be random.)
Check out my axe example on any world, if you doubt.
With each new level of shop a certain number... and TYPE of Item is added. A couple low level things,
a hat, a new coat. The type of item is NOT random. You do not see 3 or 4 fancy items added at a
level up, EVER! In a random system this will happen. Believe my theory or not, some kind of 'template' is
already coded into the shops for insertion of new items at Level up. I do not claim to know how it works,
just that it does.
Item stock in shops is in NO WAY truly random! Unlike product drops, there are patterns... of exclusion!
Pick any clustered group of of towns on the map. With the Exception for one, or two items their stock is
nearly identical to each other!! look at another nearby cluster. Different... but the same. (Within the group)
Look for some Items like the Lumberjack Axe, a high level firearm, or Fancy Cotton Jacket.
I've convinced myself. I have done a lot of 'shopping'. If there is not a manufactured "Pattern" in stock
distribution I'll eat my fancy cap!