Can I challenge this ridiculous claim?

Recently, my 14-year-old son fell from his bike on the school’s campus and hit his chin to the ground. I received a call from the school nurse and went to pick him up. The nurse provided some first aid (put a bandaid) and suggested that we take him to a hospital for stitches since the wound was a bit deep. Just to given an idea about the severity of the wound, a simple bandage was able to stop the bleeding, and my son was not even feeling any pain. She also recommended getting a CT scan since he had passed out for a minute or so.
First, I took him to our regular pediatrician, who said that she cannot do the stitching and suggested going to the emergency room. She also mentioned that there was no need for a CT scan. Then, I went to a hospital’s emergency ward. They made me wait for about 30 minutes before admitting us. Later, we were asked to wait in a room for about 3 to 4 hours without any attention. Later, they told me that a specialist was needed to perform the stitches. So, we waited for a couple more hours before the specialist arrived. He introduced himself as a cosmetic surgeon. He completed the stitching (5 stitches) in 15 minutes, and we were discharged.
Now the Billing Part: (I have a pretty decent medical plan with UHC through my employer. )

First, the pediatrician charged around $250, and with the insurance discount, my copay came to about $100. The hospital claimed about $3,500, and the insurance discounted it to $2,100, and they pay nothing. I am now responsible for 2.1K

The most surprising charge was the surgeon’s bill of $19,500, which the insurance company reduced to $208.39. I would like to understand how do these things work?

I understand the medical system here in US but this entire treatment could have cost around $100 even without insurance, if it had happened outside the US (I have lived in Asia and Europe before moving to the US).

I am wondering what I could have done differently and if I can negotiate the hospital bill.

TLDR: My 14-year-old boy fell from his bike and hit his chin, requiring stitches. The hospital bill was $2,800, the surgeon’s bill was $220 ($19,500 originally), and there were additional copays for prescription medications. I am wondering if there is anything I could have done differently to avoid such high medical costs.