Most of these don't apply to doing business nowadays simply because they're based on a mindset that worked for a different generation of people. They're also heavily dependent on context and affiliation, most mobsters had a code and would stick to it but no regard for morals or consequences/rules when it came to dealing with civilians. Let's not forget that most of those individuals were outlaws, psychopaths, criminals in general and they a lot of them ended up breaking rules when it benefitted them. After all, snitches turning stories into confessions, books, movies and such.. is the ultimate example that these rules don't stick.