For me, Columbo episodes were two types - where Columbo actually uses smarts to solve the case (like Ross Martin episode) and the ones where he just hounds the killer into confessing with absolutely no evidence. Or worse yet, like the Laurence Harvey epiode, where Columbo’s “solution” is bass-ackwards*.
If these killers would just shut up, they’d never get convicted. The Law and Order fan in me says a lot of them get acquitted at trial.
As for Bannercheck, there were episodes of actual theft. The prototype car on the train was an actualy clever theft. It would never work in real life, but it was clever!
Banacek had two problems with his episodes. One was the show cheated. They never anticipated their audience being able to rewatch, but in several episodes, when you see the crime in the beginning, and compare to Banacek’s end of episode “here’s what happened”, there are differences!
The other was that, in for example the case of the missing wedding carriage, where the container was “switched” (no spoilers!), any competent investigator would have assumed some sort of switch, and opened every container still on the dock. Don’t need Mr Ten Percent for that. Evern Carlie could have figured that out! 
*the case involved Harvey’s charcter, who was deaf, murdering a guy by shoving him into an industrial trash shredder. But the device had a safety, so that it would stop if someone fell in. I guess he fell in enough to be mortally wounded and bleed out, rather than be shredded. Anyway, it looks like a tragic accident. But Columbo figures, well IF someone pushed the guy in to murder him, and the machine stopped due to the safety, then the killer would have noticed, and finished the job. But since the machine, which was very noisy, stopped, then only a deaf person wouldn’t have noticed.
But you see, since the guy actually DID die, even with the safety, it still could be explained as an accident. And if Harvey has just shut up, he’d have skated.
Still, Columbo’s thinking is wrong.