They make buckets of money off of most peoples' insurance companies, so they can afford to essentially give medications away or discount them greatly to a select few. For example, I take Lialda. I pay a $75 per month copay. I think it's about $500 without insurance. My insurance pays the difference (likely they work out a sum that is less than the $425 difference, but still, the Lialda people get way more money from my insurance company than they do from me). And that's not even a particularly expensive med - when I was on brand-name Entocort (before the generic budesonide was available here), it was at least $1000 per month before insurance, but again, I was only paying $75 and my insurance paid the rest. And yeah, the biologics cost a lot more than that. These companies make money hand over fist and they don't want to look bad, so they offer assistance to people who need it because they can easily afford it. (I'm not anti big pharma, this is just my understanding of how the system works.)
Yes, it is ridiculous what is & isn't covered. A few years back when I had the pill cam, I had inquired about having the patency capsule (dummy pill cam that dissolves if it gets stuck) beforehand just to make sure the pill cam itself would pass through me okay. I was told no, because the patency capsule for some odd reason costs as much as (or possibly even more than) the pill cam itself and isn't typically covered by insurance. So, if I had the patency capsule, I'd be on the hook several thousand dollars for literally taking what amounts to one sugar pill. And if the pill cam had gotten stuck, my insurance company would have been on the line to pay whatever emergency surgery costs to remove it. Insane! It seems to me like the patency capsule should cost, like, a dollar. It's very odd how these things work.