Outside of Jack Webb I don't think you could make a better case for a cop being totally professional than with Jack Lord as Steve McGarrett. Even with Webb you got hints of a private life usually in the squad car as he and Ben Alexander or later Harry Morgan rode around between locations on an episode. In fact usually TV series last because of various personal dimensions gradually introduced into a series for the characters.
But in Hawaii 5-0, never. Lord was appointed by the Governor of Hawaii to head a special state police force to really go after the high level crooks. His jurisdiction was pretty well anywhere he wanted it. I never saw any complaints from Honolulu PD or any other local police entity about it in the 12 years Hawaii Five-0 ran.
Lord had a picked team with James MacArthur, Kam Fong and several other local players from Hawaii as other police assigned to him. Richard Denning made some appearances every so often as the governor. In fact MacArthur as Danny Williams was the guy that McGarrett ordered almost every week to 'book 'em Danno' in the show's most celebrated catchphrase.
Hawaii Five-0 had three great things going for it. The first was Hawaii itself. I for one can't get enough of the scenery. It's the most beautiful place on the planet and that's on several different levels. I don't the show would have lasted twelve seasons if it was done in East St. Louis.
Secondly the writing was extraordinarily good matched by the editing. I don't recall a frame of extraneous film in any given episode. Like McGarrett and his team, every show got right down to business and moved.
Lastly it was Jack Lord who created a character that solely and totally focused on his job. Normally those are not warm and fuzzy people, but the absolutely incorruptible Steve McGarrett was a guy that any citizen would want to know is serving and protecting. Even if he didn't seem to have a personal life.
To live and work in Hawaii, it doesn't get better.