Why does the price of loratadine go up (per pill) in boxes that have more?

Question

Normally packaging of stuff gets cheaper as you get to a bigger package. 10 pills box of loratadine was $2 (not on sale or anything), while 30 pills was $12, rather than something cheaper than $6. (The pills were exactly the same amount and both 24-hour). Why is this packaging different than other things that are a better value as the bulk goes up?

Answer 1

An idiotic retailer screwed up the pricing.

Answer 2

The law of  diminishing returns