Okay…explaining it. I said that with every intent on expanding my idea, but I didn't quite have my thoughts on paper. Now that I've gathered my thoughts, I can explain it.
From stories and books which take place in Japan that I've been reading, there's this philosophy of “the group comes before the individual.” I think one of the reasons why nobody would want to start a GB franchise in Japan is because of how destructive it is. Destruction is pretty much the appeal of Ghostbusting–you strap a thermonuclear accelerator onto your back and lay waste to your surroundings, thereby disrupting the everyday order.
As a matter of fact, that becomes a major plot point–our heroes redesign the equipment to make it less dangerous.
Oh, yes–there's also the fact that the Proton Pack is a miniature nuclear accelerator. I read a book about the otaku subculture called Little Boy: The Art of Japan's Exploding Subculture, which stated in no uncertain terms that the bombings of Hiroshima and Nagasaki changed just about everything in Japan forever. Not just the physical effects of the bombs, but the psychological and emotional effects, which might still be felt to this day.
Again, this becomes a plot point–they try to make the equipment a bit less nuclear by introducing a rechargeable “fuel cell,” as I call it. It's a nuclear battery, of course, but it's safer than what Drs. Spengler and Stantz built (i.e. less parts to worry about, less risk of contamination).
There might also be some sensitivity issues concerning the very practice of Ghostbusting as opposed to busting ghosts…a Ghostbuster essentially captures a ghost by force and shoves it into a storage facility. There is this idea–I can't quite define it–that all things, living or otherwise, have souls, and the Ghostbusters' method may be seen as a violation of that philosophy.
The solution, here, is to state that the Containment Unit is a temporary measure…the GBJP version of the ECU is a kind of solitary confinement where the more violent ghosts are kept to “cool down” enough until the Ghostbusters can deal with them in a more constructive manner. In theory, this works just fine. In practice, this may present a few problems…
There's also the idea that Japan's economy doesn't really reward entrepreneurs. That's why a “sensible” businessman would leave a GB franchise alone…it A)is an untapped niche, B)is extremely dangerous, C)doesn't readily lend itself to consistently healthy profits, and D)deals with something that can't easily be qualified.
Okay, I'll admit, I may be talking complete bollocks. But books such as American Fuji have pointed me in this direction. Besides, it serves the “going into business” narrative quite well: a wild new company, struggling to find a foothold, suddenly makes it big.
(PS: That big long rant above got me thinking: the new equipment probably won't be unveiled until halfway through. They continue to use the old-style stuff until Eguchi buys the company, at which point he guarantees them enough money to enact the redesigns they'd been planning.)