How is it any time someone mentions government-provided single-payer health care or more investment in public transportation systems you hear all this outcry of "Socialism"?

Of course they're also another example of a "socialism" mindset.
Countries ARE societies, after all.  And what is the root word of "society"? "Social", right?  The same root word of "socialism", no?
All societies are (at least in part) socialist in nature.  Otherwise why call them "society"?  It's been that way since the beginnings of civilization.  The only alternatives would be self-rule----which would require large sparsely-populated ultra-rural areas wherein one could have full control over their physical and natural environment.  Or anarchy, which entails being strong-armed into submission by whoever has either the most brute physical strength, the most charismatic persona, or a tremendous aptitude for influencing others---in the name of establishing some kind of "social order"---itself a perverse incarnation of the "socialism" concept.

We live in societies that provide streets, roads, and highways to travel on
...that write laws "everyone's expected to abide by" under consequence of punishments (inequitable enforcement aside)
...that are affected by whatever industries and corporations are successful in providing select goods and services to the civilian population, business, and government factions for an exchange (a.k.a.: financial profits)
...that have educational systems whose officials are in charge of providing whatever materials they deem fit to teach those still growing up
...that have authorities who act as "agents for the system", whose job is to coerce the general populace into complying with the ways of their society, under threats of various punishments for anything perceived by the "system" as being of a defiant or heretical nature
...that have government agencies regulating finance, environmental clauses, "safety net" benefits, traffic/transportation safety and operations, business practices and ethics, revenue/taxation---and the like.

So, to those worrying about the "free" western world slipping into a "socialist" state----you're wasting your time.  All societies are "socialist" by nature to begin with.  Always have been, always will be, regardless of professed form-of-government.  A society could never be a "society" otherwise.

Oh, ahhh...
Be sure to file your tax returns on time.  Wouldn't want to piss off Uncle Samuel, you know.  "He" has authority to take all your money, all your property, all your assets if "he" so chooses, as a lot of you well know.