Do you think these are works of the same "artist?"
If they are, he sure gets around a lot.
Small industrial units are the playground for the hack or the DIY tenants themselves. Many of these tenants are bottomfeeders, and the idea of hiring a real electrician to do their work for them just runs contrary to their nature.
Cord is the weapon of choice. Other favorites are romex or romex inside of flex and 14/2 MC cable.
I often have to make units like these leaseable after a tenant moveout. The number of KO seals, cover plates and CB filler plates I go through is staggering.