I'm going to go out on a limb and risk saying DCS jobs are not as common, but likely to be higher paid mostly due to it not being easy to gain experience without having a way in.
I can buy an Automation direct or load Codesys into a Raspberry pi or even download TIA Portal and play with a PLC, but I can't download PCS7, PlantPAX or DeltaV (I can't even find manuals on DeltaV to be honest), to play with it and at least have a bit of opening towards it.
[rant]Although, if you're looking to be hired by an automation giant (Siemens) to work on their DCS system, get ready to be insulted, belittled and offered a **** salary so they can get you on the cheap. [/rant]