where is the waste in our healthcare, giving grandma an operation?

Part of the "waste" I think you are referring to, relates to subsidies paid by the government to the insurance companies to supplement the premiums.

Once a public option or single payer system is in place, these subsidies or "waste" no longer exist.

The system run by the insurance companies needs 30-40% for overhead and profit. The single payer or public option will be run on less than 10%.