I can speak to this with some authority.

On typos, etc. - that is a product of the editor and way books are published. Things get rushed through the process. At some point, as an author, you've gone through the book so many times and ran spell check that you can't do it anymore and need a professional editor to hack it up. Some are better than others. My editor for The Silent Don did a great job. My current editor for Cocktail Noir, is fantastic. It really depends. And it's not just mob books, it's all books.

Some typos do not get picked up by spellcheck. My two big typos are typing "form" instead of "from", and dropping an "s" from a previous word onto the beginning of the word "in", which is 'sin'-spelled correctly!

Accuracy - The field of mob writing is constantly shifting with new information, new 'rats', new people coming forward. The narrative often changes, as do the facts. Generally it's minor stuff, but sometimes not. You are always limited by the information you have available to you as a researcher or writer.

Sometimes it's lazy research for sure. Sometimes it's not vetting sources you cite. But most of the time, it's because you have limited information at the time you write.