You are forgetting, if your level is low, you would most likely not find any other than ingredients to craft them - it's why you find Aloe cream 99& of the time at level one.
Your best bet at early levels is to place 1 rank in lucky looter maybe find looter goggles and sneak into the wasteland biome...
Specific understanding in game mechanics matter more so than RNG.
Not true in this case. Vitamins are in groupMedicalUncommon just like First Aid bandages, painkillers, Herbal antibiotics, Plaster Cast, Steroids, and blood bags (though the antibiotics and cast probabilities are set to very low and low). Most of the container groups that I found that have this group in them are set to med or high probability which is not tied at all to lootstage. So as an example, the small medical piles you find:
<lootgroup name="groupMedicalPileSmall" count="all">
<item group="groupMedicalSmall01" count ="1"/>
<item group="groupMedicalSmall02" loot_prob_template="med" force_prob="true"/>
<item group="groupMedicalSmall03" loot_prob_template="low" force_prob="true"/>
</lootgroup>
So you will definitely pull something from Small01 which has 3 groups (Common - high, Uncommon - med, Rare - veryLow), 50% chance of pulling something from Small02 group (same groups and probs as Small01), and a 20% chance of pulling something from group Small03 (again same as the other two).
You find aloe cream because it is one of 4 items in the CommonMedical group (two of which are set to low probability in the Common group) which has a higher chance (75%) of pulling from in all 3 cases. Putting the lucky googles on might make you feel like you are more lucky, but the universe is just laughing at you
You have the same chance of finding vitamins in a small medical pile at level 1 with no gear in the pine forest as you do at level 60 with all ranks of lucky looter, goggles, and searching the pile in the Wasteland.