It's got a bit more depth to it that waifu gacha...
Although in-universe, the T-dolls are literally civilian waifu bots being given guns
if Sanguis Ferri are using Humvees, we're using Toyota Hiluxes
VVV
What's the lore behind that? What did they do as civilian bots?
I'm pretty sure that isn't actually the case.
Digging into the wiki, initial development focused on creating autonomous and largely self-sustaining workforce (which makes sense in light of double-apocalypse due to North Island Incident and WW3), until Pan-European Military Union put forth a request for an autonomous robot to control their tanks. The "T-Doll" largely grew out of that project.
Actual military T-Dolls do not resemble our models at all; they are pure killing machines with zero emotive capability, largely because they forgo cute waifu personalities in favor hardened shells and maximum killing power, which is why in one-on-one combat, your average G&K T-doll is hosed against KCCO one.
G&K uses converted models largely because Kryuger made it a business niche; They make better peacekeeping forces and bodyguards, and converting a Doll into weapon is still cheaper than finding a willing volunteer soldiers in AD20XX. It's kind of the-other-way-around solution: T-Dolls were military tools, then were adapted to civilian market, then G&K reconverted civilian models back into military ones. It's also probably why retired T-Dolls can just switch to civilian sector; they can still do other jobs.
A KCCO (and to lesser extent, most SF) T-Dolls only know how to kill people.
What do you think they did?
As many functions there might be in diminished society, I will admit this would be probably the primary reason why anyone would buy T-Doll companion. Skeevy but true.
Especially since something like 70% of the population are dead anyway.
...makes me wonder if there are really buff, Schwarzenegger-style male T-Dolls out there as well.
Helian would certainly want one.