You are exactly right, "Nothing to hide" is also an invalid argument - because a valid suspicion of criminality will be authorised for subpoena by a judge.

Without such oversight we immediately and repeatedly see abuse of these systems: here's just a tiny list of cases where the "good guys" abused their access to systems to stalk ex-lovers and people they found attractive.

This underlines why the "good guys" argument is both invalid, but deliberately misleading. We don't plan systems and security around good guys, we plan them around bad guys.

USA:

N.J. cop used police databases to stalk ex-girlfriend, investigators say

https://www.nj.com/monmouth/2023/01/nj-cop-used-police-datab...

Officer Fired for Allegedly Using Police Database to Stalk, Harass Women

https://www.newsweek.com/officer-fired-allegedly-using-polic...

Australia:

Former policeman accused of using force database to stalk ex-wife and girlfriend

https://www.theage.com.au/national/victoria/former-policeman...

Former federal police officer faces new charges over stalking of ex-girlfriend

https://www.canberratimes.com.au/story/6138318/former-federa...

(Note the two above articles are not the same person)

UK: Met police officer 'used CCTV cameras to stalk his ex-girlfriend after telling her to take up sex work to pay her bills'

https://www.dailymail.co.uk/news/article-11868575/Met-police...

Creepy cop saw attractive woman on the road and 'looked up her license plate number so he could stalk her on Facebook'

https://www.dailymail.co.uk/news/article-2178556/Officer-Jef...