This type setup here is referred to as a 'mat job'. Yes, it is 'old' technology, and is slowly going away. Three or six pots was standard before pad mount units. 250, 333, 500 KVA were common, occasionally 750s.
Today, when there is a failure in an existing mat, the failed pot will be replaced, or the full set may be replaced.
AS to the building in the pic, yes it is vacant, as the avionics co that was there outgrew to 65k SF.
As to the vegatation, sorry to say it is 'common' with mat jobs. The transformers, primary pole and wiring are POCO owned and maintained. The fence is locked with a POCO lock. The POCO does provide forestry work, but most of the time it is done after a failure, blown cut-out, etc.
Guess this is not something you see on the west coast??
The transformer farms are fairly well maintained here, at least the fence and the weeds. They spray enough herbicides around to be sure nothing is growing. We have weeds here that could completely cover a transformer like that in a month.
Seen a soil sterilizer that was used, nothing but bare earth,without it there would have been Star Thistle & other noxious weeds. Suspect that it would have to be applied by a licensed applicator though.
The generally abandoned nature of the site makes one think that the primaries were de-energized.
Out my way the AHJ have prohibited this type of service whenever and wherever possible.
Instead, primary distribution occurs underground with pad mounted transformers -- feeding bus-duct taps (see photo above) by proximate placement as necessary. (Bus-duct taps establish fire isolation, FYI)
This style also takes weather out of the equation and saves on real estate.
Hereabouts the cost of trenching is very high. The ice age glaciers scraped off all of the topsoil, leaving rock and some dusting on top. None-the-less, underground distribution is mandated.
The Pocos have discovered that underground distribution largely eliminates weather crisis. Crisis labor rates are out of this world. (plus bad politics)