Cotton, I don’t know where you got that idea that all new homes came with fire-extinguishers. It has never been a requirement in CA or WA unless like Spirit says in apartments. But that might not be the case in CA now. If I am not mistaken I think I read or heard CA is requiring ALL new homes have solar panels on their roofs so maybe fire-extinguishers are also a requirement now.
National Fire Protection Association requirement for portable fire extinguishers

Apartments need them at exterior exits and on the interiors within 75 feet of all parts of the building. One and two family dwelling occupancies do not require extinguishers.
Various jurisdictions can have different rules, of course. And it could be like Spunky said, insurance companies give discounts for extinguishers. Some policies might even require them.
Now I just think the house has came with them but that we were required to get them. I guess it’s just my dad always had one under the sink. And now my husband has fire extinguishers all over the place. At one time he was worried about spontaneous combustion. I had forgotten about that.
Actually now California requires that every new home comes with an automatic sprinkler system in the ceiling. Crazy, and not inexpensive! And how often do smoke alarms go off when they shouldn’t? Great idea, soak everybody’s furniture and carpets. I would imagine insurance is higher with those things in, ironically.