If that includes the OR fee, Doctor fee, and room fee, it sounds about right. Most hospitals in the US have charity options if a person cannot afford the bill, or they have payment plans you can work with. I have found as long as you send them some money each month they are happy.
I had two emergency room visits last winter (thankfully all was ultimately OK) which ran about $4,000 EACH, $8,000 total.
The hospital and subsidiary providers were all very amenable to a range of payment options.
$28,000 sounds right for an emergency appendectomy.
If I ever need elective surgery I’m off to Thailand, India, or Malaysia, all of which provide superior medical care at low cost.