Journalists are just people. Reliable journalism occurs when those people try their best to provide accurate information, and when they make a mistake they correct it. That's it. You can't expect perfection from people.
The CNN fish feeding story was deliberately created by zooming film at the point the Japanese leader dumped their fish food, then zooming out again to show Trump dumping his, then writing text to support the fake narrative.
The Mark Duggan 'unarmed' headline was immediately followed by a story which revealed the suspect was armed.
The retracted CNN Russia stuff might have simply have been gross incompetence though so your point does apply there.
It is not enough to trust them to do their best. Journalists should be in a structure that strongly incentivizes telling the truth and strongly punishes false information. It is very unclear that US media outlets, almost all of which are highly politicized, have this property.
Really?
https://en.wikipedia.org/wiki/Dan_Rather#Killian_documents
https://en.wikipedia.org/wiki/Brian_Williams#Iraq_War_helico...
https://en.wikipedia.org/wiki/Juan_M._Thompson#Reporting_sca...
https://en.wikipedia.org/wiki/Jayson_Blair#Plagiarism_and_fa...
https://en.wikipedia.org/wiki/Lara_Logan#Benghazi_report_apo...
https://www.timeout.com/chicago/tv/how-a-horrible-decision-c...
https://en.wikipedia.org/wiki/Michael_Finkel
https://en.wikipedia.org/wiki/Stephen_Glass#The_New_Republic