Bail, O.R. in the Typical DUI case

In the ordinary course of a drunk driving arrest it is typical for the arresting officer to book the suspect after he determines that the individual was intoxicated, at this key time the jail has the choice to either release the person from custody with a signed promise to appear in Court (known as O.R.) or require the posting of bail. With increased tension from MADD and other groups many jailers are opting for the bail route, even though the accused is of little risk of flight. Is this right? your comments are appreciated.