The direct cost to the consumer is $0 (or lira, or EU, or whatever), but that's because public healthcare negotiated with the power of a volume customer to agree on a fixed price, which is paid for by the government, which is paid for by people's taxes. So what you're doing is spreading the cost of the drug across the population. I had a similar situation when I had kaiser- no out of pocket costs.

As to why drugs are expensive in the US: because the market bears it. Demand is just elastic enough (or inelastic, I always get it backwards) in the US that providers slowly edge prices up. Sometimes they get it wrong for example aduhelm didn't sell so it had a huge price drop recently.