Can a bench warrant be issued for failure to pay medical bills?

No. A bench warrant is a method used to compel appearance for a criminal or quasi-criminal (like traffic tickets that require an appearance in court) matter. Failure to pay medical bills is a civil action. The courts do not arrest people or compel their appearance for simple failure to pay a debt. If a defendant fails to appear for a civil trial, the court will enter a default judgment against the missing party, but will not issue a bench warrant.