In my old WW towns I had oranges twice and cherries once. Now I have pears in NL. I probly wouldn't have picked pears as a most wanted fruit, but I've grown pretty attached to them. Especially the golden perfect pears! They're pearfect.
the only rarity would be from players choosing to have certain fruits and resetting until they get them (which in that case, I'd hazard a guess that pears are the rarest)
but as far as in-game statistics go, it's just rather evenly spread randomization