A lot of the average person’s understanding of the world that is all around them comes from things like the TV shows that they tend to watch on a more or less regular basis. These TV shows usually have a few tropes, and many of these tropes involve stock characters who are easy enough to write in a compelling manner. Lawyers, police officers, drug dealers and other such people are very popular stock characters due to the reason that they are already interesting enough thanks to what they do on a daily basis and not all that much effort needs to be put into creating an engaging backstory for them.
Another stock character that is quite commonplace in several different TV shows both historic as well as contemporary is that of the private investigator New Orleans. PIs are sometimes portrayed as noble individuals who are just trying to do the right thing, and this might just be the only example of some kind of a profession being portrayed accurately on the silver screen at the very least to a certain extent.
At the end of the day, the things that a PI would do over the course of a regular workday usually depends on what their client has hired them for. They sometimes try to get evidence that a spouse is cheating, or they can be hired to uncover any kind of fraud that might be happening in a particular business. Official police departments also sometimes work with PIs because they are not bound by the same restrictions and can often start moving the investigation in the right direction by providing advice and information that police might not get their hands on.