The usual term with things like plumbers is "rollup". Even the most delusional excel jockey probably doesn't believe he has 'operational alpha' vs. a veteran plumber in matters of plumbing; but he(correctly) knows that local plumbing outfits are a fairly heavily fragmented industry with a lot of relatively small players; the sort of quaint folksy thing that looks like one of those competitive free markets they told you about in EC101. And, if you, purely hypothetically, can borrow money for a pittance, you don't need to improve operations when you can just buy a bunch of the small players, consolidate them, and then raise prices to match the newly reduced level of competition.
Same deal works with more or less any business with a lot of mom 'n pop operators; as well as things like rental housing. Maybe there are some marginal efficiency improvements in back office functions because it's not eleventy zillion individual copies of quickbooks; but most of the actual margins come from the higher prices you can command from customers and the lower prices you can offer to suppliers and employees once you consolidate a given sector in a given area. The effect is particularly lurid when it comes to thinks like small medical and dental practices; or care homes; since there it's about the money; but being about the money is also about pushing your employees to recommend unnecessary implant surgery and cutting patient/staff ratios as hard as you can without anyone noticing too many bedsores. Fantastic stuff, really.