Most of the work in/around DCs is contract of some sort. Local structured cabling firms, electricians doing stints of various lengths, security, etc. Some of it good and lucrative, some of it not.
Most of the overlap I see is when there is a commercial building collapse (economically, not literally) and you end up seeing master electricians working on residential. Much more rare to see the opposite movement unless it's a permanent change.
Not only that, but the trades stick to their trades.
You don't get, for example, datacentre electricians rocking up pretenting they can install network cable to spec and running away having (if you are lucky) only done a continuity test on the cable they just installed.
Meanwhile every man and his dog, or even just the dog, will very happily turn up at your house and tell you they can install your CAT6 to spec for you when they've never seen a Fluke in their entire life.
Needless to say I've re-pulled a lot of those cables due to so many failures.
We had to redo and re-pull so many circuits in the last datacenter project.
I frequently have my electricians pull and terminate network cable if it’s only one or a few (daisy-chained VAV controllers or a network drop for a BAS panel), if the customer needs a formal TIA-568 test then I’ll sub that out. My electricians are already pulling and terminating building automation cable, CAT 6 isn’t gonna stop em :)
I’d like to learn more about PLCs and SCADA, but that scope of work usually falls on another contractor, we mostly provide installation for BAS systems that control HVAC and chilled/hot water plants.
I do some water treatment plant projects and there’s a local contractor that handles the PLC and SCADA stuff.
I want to know what country you live in that you can find domestic tradespeople who will do work to the same standard as datacentres, and do it at domestic prices. ;)