I'm not the original poster but I'm from Croatia. I've been living in the US for around 10 years now and have a chronic illness that required constant management: Type 1 Diabetes.

I also have a separate issue, Pectus Excavatum, a chest deformity that required me to undertake a fairly difficult surgery called the Nuss Procedure.

I think these two examples do a good job at demonstrating differences between Croatian an US healthcare payment systems. They are very different medical problems.

Diabetes is a chronic illness that requires constant management. I need to inject insulin multiple times a day and require other supplies such as sugar sensors, lancets, needles, and glucose strips. I have a brother who still lives in Croatia and also has Diabetes Type 1. Our treatment plans are almost identical. We take the same medications and need the same supplies.

Managing Diabetes in the US is fairly annoying and expensive. I'm lucky to work in tech which provides me with good pay and insurance but even then my expenses can go up to $200/mo. It is also difficult, sometimes impossible, to get insurance authorization for better insulins that are widely available in Europe. I am on Humalog, or sometimes Novolog, similar insulins but insurance companies only cover a single one, so you have to switch when you change insurances. Newer insulins such as Fiasp, Apidra, or Tresiba, which are newer, quicker to work, and overall "better" are almost impossible to get in the US. I tried multiple times and the insurance never gave me the authorization to use them.

My brother lives in Zagreb, Croatia. He's been a diabetic all of his life. He's using newer insulins such as Fiasp and Tresiba and he doesn't pay anything for them. Literally 0. It's completely covered by the National Insurance. Same goes for all of the supplies like strips and needles, and glucose sensors (which can be pretty expensive in the US). In total he pays $0.00 on diabetes management.

In addition, Diabetes education is terrible in the US. Doctors here will usually tell me that I can eat whatever I want as long as I cover it with enough insulin. This is just awful advice since people are not computers and will never calculate the correct dosage of insulin they need to cover every meal; resulting in bad sugar management and complications that come with it: blindness, limb amputation, and eventually death.

The ONLY way to properly manage diabetes is to be very careful about eating carbs. Not necessarily eliminate them, but come as close to it as possible. This is the way diabetes education works in Croatia. Fix the diet and then use insulin to fix what you can't fix with diet. The result is way better sugar management, and way cheaper treatments.
Just the other week I had my checkup here in the US and the doctor told me my blood sugars are "too LOW for a diabetic" (my A1c was 5.9% - still higher than the normal 5.5% for a healthy person). I should change my diet and eat more carbs to raise it up. This is just awful, awful advice and I'm sure it's the result of generally terrible diet in the US.

So overall, healthcare treatment and payment for a chronic illness like Diabetes is just immeasurably better in Croatia. It's not even a contest.

Now, on the other hand.

Pectus Excavatum is a bone deformity. In some cases it's small enough to not present any problems but if it's fairly severe it can cause a lot of cardiovascular issues. Nuss procedure involves implanting multiple steel bars (3 in my case) behind the chest wall in order to force the chest bone out. The bars stay in the body for 3 years and are then removed. Surgery is usually successful and after the bars are removed you are considered "cured". There is nothing more to manage and the rate of complications is very low.

This surgery is complicated. It's most often done on children because it becomes much more difficult to perform it in adults. Video if interested: https://www.youtube.com/watch?v=R8SrRzJqbJ8

As an adult, it's almost impossible to get the surgery performed in Europe. I know there's a center in Italy, and another Netherlands that do perform it, but their rate of success is not great. I've seen a lot of people complain about the results.
The place to do it is the United States. Mayo Clinic in Arizona has the absolute world expert on Nuss Procedure and she does surgeries on adult of up to 40ish years of age (I got in at 37, last chance). Her work is absolutely phenomenal and people from all over the world travel to Arizona to do it there. There are also hospitals in Missouri I think and in New Jersey that do it, but I'm less familiar with them.

Now given that there are only a handful of places in the world that perform this surgery on adults, you'd think that the cost of this procedure would be astronomical. In total I paid around $2000 out of pocket. Without insurance it costs around $30k, plus $10k or so for the hospital bed (oh US). Don't get me wrong, it's not cheap, but for something of such difficulty and expertise I expected it to be way more expensive. It's literally impossible to get in most of the world other than the US and it costs less than the price of diabetes supplies for 1 year.

So there you have it. In my opinion the US system is absolutely awful for managing chronic conditions. It's made to exploit you for as much money as possible and even give you bad medical advice that makes sure you're going to need those expensive supplies.
On the other hand, the most difficult procedures in the world are sometimes only available in the US, and the price of those is not nearly as high as you'd expect it to be.
It's great for acute treatable conditions, and absolutely awful for chronic conditions that require constant management.