it's called liability since part of that extra cost goes for the Extra malpractice insurance that goes along with surgery vs a screening procedure, and they aren't just skin tags, snare one wrong and you have a hole in your colon... then it becomes real surgery to fix it and if they don't know it was a through hole, you go home with a perforation that leaks feces which can REALLY cause problems... something the mechanic doesn't have to worry about
blame the lawyers for the extra cost of practicing preventative medicine and the high cost of malpractice insurance