Am I missing something re divination cards?

Stacked decks sell for a crazy price on trade, that doesn't reflect the actual expectable value of the drops by far.

Or are stacked decks better than normal divination cards when it comes to higher tier drop rates?

Not currently in trade league but they usually go for about 1c from what I have seen.
In ssf I would say stacked decks are also fairly ballpark to 1c in value.

While most div cards are worth less than 1c, there are some that are worth a lot more, for example, house of mirrors is one ninth of a mirror. The lowest price I can see on trade currently in crucible league is 80Div which is something like 15000c, maybe more.

So it is a heavily skewed distribution. If you calculate the expected value of all card outcomes across the set, I would assume it is pretty close to the price the market is setting.

I think that it is likely stacked decks are very slightly overpriced from the expected value, as it gives the opener of the deck the chance to gamble and increase their variance. There may be some other factors that impact the price, for example I've notice some streamers/youtubers like to open bulk amount of random outcomes to show to their audience. It's also approaching the end of the league so perhaps holding staked decks has some value during league migration, i'm not too sure.

I'm not sure if the drop rates are better/worse in any cases, think they are about the same, but someone else might be able to clarify.

Stack decks have the same drop rates as div cards. What you are seeing is the gambler's premium. It's the same reason people go to Vegas: While most will lose, a select few will win and everyone (mostly) has fun.

This league, I got an Apothecary in the first 10 decks I found. So I laughed and took it to the Rhex Gambling Casino, which promptly ate the card haha...

Haha

I see on the wiki apothecary has a drop level 75, stacked decks is drop level 50, so I guess there is some sort of reality where it's possible to have mageblood before entering maps? Decks can be opened anywhere, whereas ancient orb need to be in the tagged area, is this correct?

Stacked decks are profit (on average) at their current price. You just need to do a LOT of them to get the average to show itself.

There has been a lot of science done on stacked decks, very interesting stuff. I believe they reflect the drop weights of the cards? Most of the interesting stuff is on reddit in posts by poorFishwife, but you can ask in the Divcord (https://discord.gg/mpnYHbxHXs)