I’m not saying it’s a good system, just that there’s no reason for anyone without insurance to pay the unrealistically high list price.

There are discount cards that work with insurance, too. Like a drug with a $10 copay might have a discount card that fully covers the copay. You just have to do a little research before going to the pharmacy.

In the US, pharmacies absolutely compete, but the model is complex. They are delivering service to a party that is not always the one paying (Patient vs. Insurer). They can dispense the same drug from multiple suppliers with wildly different costs in some cases (Original vs. Generic). Most of their customers have some sort of coverage, so the coupons don't apply. The drug companies really hate when their are articles about people dying because they can't afford meds, so they have coupon programs for the uninsured, but keep the list price high since that is the starting point for negotiating with the insurers.

Don't forget that doctors are completely disconnected with cost. They don't even know their own rates that will be charged to the patient in many cases, let alone what the cost of drugs are, and what portion of that the patient will end up paying.

So on the patient side, the pharmacy will compete for patients with convenience, while the insurer will try to steer the patient to approved generic drugs and manufacturers with negotiated deals, while the drug companies are trying to steer the patient to the most expensive name brand drugs. Oh yeah, and then there are the unlucky minority that don't have insurance or have insurance that won't cover the drug they need, and they get a coupon.

It is SUPER fucked.

The answer is that there are at least four parties in any pharmacy transaction (Dr., Pharmacy, patient, drug maker, and sometimes insurer) that all have different incentives. Some that overlap, and some that are opposed.