Im Working in an Industrial setting and there is cabletray that goes in every direction with SO cord in it that transitions to a cord drop (with strain relief) for work stations (120 volt outlet). There are also air hoses run in this cable tray but I'm not going there!!! I thought type TC multiconductor cable had to be run in cable tray. I would love to point out to the plant supervisor that I could make this code compliant for him (plus we could use the extra work).
Odds are you will get the "it's been working fine for years" reply. I would do my work to code and mention that all the other is not. It is basically up to the people paying the bill to have you make the rest code compliant. (been there done that). The only time I have ever had anyone force a facility to bring existing up to code was when their insurance people required it because of the areas classification. (I.E. Class I division II)