Tavy
Because it can dissolve on its own or come out when you pee. My husbands did.
Diane A
Because you can have bladder stones for life with no problems, so no need to do anything unless you have issues.
Anonymous
You are lucky that your urologist is taking the conservative approach of "if it ain't broke, don't fix it". Today most doctors would subject you to ultrasound, radiation and surgery just to line their pockets - even if you have no symptoms.