The purpose of a fine for doing something illegal is supposed to be corrective. If a person can not pay the fine, if they're not further inconvenienced by being arrested and sent to hours until jail; the effective corrective action is being applied to the judge, police; They can arrest the same homeless, mentally ill, drug addicted person each day; or put them in prison where they don't belong -- or they can fine/arrest violent offenders or people who are "corrected" by a jail time or fine.