It has become a core function, but it wasn't originally. The first police in the US was Boston in 1838. Sixty years after our nation was formed (or 50, if you mark it from the adopting of the Constitution).

Fire is even more recent. For most places you had to pay for fire protection. They would roll up to your house, and if you hadn't (or didn't) pay, they'd let your house burn down. I remember this from discussions we had many years ago. It is now considered a "core function", but it wasn't for a long time.

Communities came together and said "hey, this is a good idea...we'll all chip in and make it happen via government". That's socialism.

The US Constitution doesn't call it out. Maybe some states' do, but I'm not aware of any. They all took it upon themselves to incorporate those as "core functions". Which is why, if you're in an unincorporated area, you have to pay someone like Rural Metro (private company) to provide that service to you.

Statements like the one you quoted is trying to obfuscate the facts and confuse people to claim "we don't like no socialism!". The population likes, and even expects, a lot of socialist programs like all the ones listed up-thread. Trying to pretend they aren't consistent with socialism is akin to that river in Egypt.