[bsder]

This is both factually incorrect and not funny at all.

In addition, last I checked, modern medicine cannot reattach nerves so you lose a great deal of functionality of your finger or hand even if you save it.

See: https://youtu.be/Xc-lIs8VNIc?t=1095

I hope I am simply missing the joke if someone would be so kind as to clue me in.

[nullindividual]

Yeah, you're missing the joke. The joke is the US healthcare system and how expensive it is.

A sense of humor might cost in excess of a finger reattachment, though.