First let's define some terms: I define "leftist" as "communist." That's how they define themselves as well. "Tankies" are a separate breed, in that they specifically idealize the Soviet Union and other authoritarian "communist" states. I am personally of the opinion that the term "socialist" is meaningless in online discourse, as few people mean it the way it was originally used - workers owning companies (which I strongly disagree with, for clarity - though I support things like mandatory profit-sharing)

Not everyone who is left of me is a Communist, though I obviously have disagreements with all of them - but then, I joke with people IRL that "regardless of your political views, if we talk long enough we'll find something I believe that will piss you off so we probably just shouldn't get into it."

As for me, my journey was largely begun through being raised in a staunchly pro-union household and working on various political campaigns (my aunt is a politician). I am very pro-union, very pro-labor, very pro-individual/pro-freedom (we'll circle back on this because this is also a Republican claim) and also very pro-market.

I'm willing to bet (though correct me if I am wrong), that it is my pro-market stance you most likely disagree with (of what is listed). I am pro-market because markets are demonstrably the most efficient way to allocate goods. I support evidence-based policy that has real impacts.

For instance, I am against rent control, because I 100% believe that rent controls, passed in an environment of massive supply shortages of housing, exacerbate the problem by limiting incentives for new housing construction. Data supports this. I also believe that any new housing at any price point increases aggregate supply and lowers pricing (though there are "tipping points" in supply that just be reached). The right way out of the housing crisis is therefore, in my view, to end single-family zoning and disincentivize single-family home ownership through higher taxes.

However, markets have limits to their efficacy, because people like to bend rules in their favor as just a matter of course. The government exists to address these externalities. This is why I support a public health option or even single-payer - I've done the math and such options save both employers and employees money. I also support dramatically increasing the number of residencies allowed, contrary to the AMA, because artificially limiting residencies restricts the supply of doctors. This organization knows this and purposely limits our supply of doctors so they make more money. Our health care system is riddled with such externalities, which single-payer or public options do a lot to address.

Rather than refine the system to address externalities, leftists (as I've defined them) want to burn the system to the ground and start afresh. I believe this will not only result in poorer outcomes, it will also result in a catastrophic and obscene loss of life. It will also implement a system that denies personal autonomy and freedom, as I see it (told you we'd circle back!)

I am a bit of an absolutist radical when it comes to freedom. I believe government can only ethically exist at the consent of the governed - so tankies are right out. I believe in free movement of people, trade as free as is geopolitically feasible, and that capital investment allows potential business owners to make dreams come true that otherwise would not. I accept limits of freedom, because we do live in a society, but I believe we often aim toward the society over the individual's actual best interest. I am deeply morally opposed to vengeance-based systems of justice and am generally a prison abolitionist. For this reason, I have the deeply unpopular belief that the 13th amendment's exception for slavery is a good thing and (paid at minimum wage) compulsory labor is better than prison for most criminals.

This got a bit longer than I intended, but it helps form the mindset from which my views come. Happy to answer any questions or hear your takes.

Edit: I am interested in your thoughts process as well.