Europeans don't typically pass nanny state laws; for example saying you can't buy a soft drink over a certain size. While admittedly some of the things the nanny state folks target aren't common in Europe for cultural reasons (like the big soda example), it's also evident that passing nanny state laws isn't a part of their culture either. Abortion restrictions are perhaps the only major way where Europeans indulge in government acting in paternalistic authoritarian ways to protect their citizens from themselves. Here in the U.S. it's not only common, it's almost a core part of the belief system of progressives that it's a needed and vital role for government to play.
In how many places have soda size restrictions been passed? It must be a lot, since you equate it to the entire US Democratic party, and separate out European left parties as not passing "nanny-state" soda size restrictions.
Oh. It was passed in one place, NY, and then repealed almost instantly. And it was an idea of Michael Bloomberg, Republican-turned-Independent. Funny that.
Nanny-state laws are what Europeans are known for. Mandated health insurance for every single citizen. Mandated paid time off. Mandated maternity/paternity leave. Mandated caps on work-hours. Etc, etc, etc. That you're forced to focus on some obscure law that was immediately repealed, in only one locale, as some great example of US Democratic party "nanny-statism" is not only telling, but hilarious. It allowed you to use your conjuring words of conservative righteousness, and it demonstrated just how much you have to strain in order to use those conjuring words. Congrats on that shit-tier example of nanny-statism, champ.
To OP:
In most European countries, the things that the Current US Democratic party is STILL fighting for are already accepted as baseline standards of any decent society. Taxes are higher, but mean that every citizen starts out getting services for those taxes. Not having to worry about how you're going to pay for a catastrophic accident or illness, or going bankrupt over it, allows the population to actually think about more than just making it through this week. Not having to work 40+ hours a week to keep up with rent, electric, and food, means that you have time to pay attention to what your politicians say, and what they actually do. And most importantly, the parliamentary systems in most European countries means that people can find candidates that aren't beholden to one-of-two sets of ideologies, making them feel as if their vote and the candidates they choose from can actually make a difference. And they expect results, because there will be multiple candidates to plausibly choose from next election.
As it should be clear to anyone who is paying attention, the US Democratic party isn't communist, or even socialist. It's centrist, relative to left-wing political ideas and philosophy. The average US Democratic politician would fit in nicely in any European center-right party. The Democrats/Independents that are maligned as communists (not because they are, but because the people making the accusations are fucking idiots and liars) would fit in with the average liberal/progressive wing of European left-wing parties. I.E. people like Sanders and Warren are your typical run-of-the-mill left-wing party member. Nothing notable, and certainly not targets of right-wing authoritarians.
First-past-the-post voting systems, unfortunately, do not foster multiple parties, so the left in the US is stuck trying to use the centrist Democratic party to make slow, left-ward advances in society. Conservative parties should typically only be used as a temper to left-wing parties to make sure that sweeping, drastic changes aren't made that are worse than the problem they are attempting to fix. But, the Republican party has been purged of RINOs, as reactionary right-wing authoritarians label sane, functional conservatives, and we're left with the current shitshow. You can thank the end of the fairness doctrine for that, as right-wing reactionary authoritarians are now the mouthpiece and thought-leaders of the "conservative" party in the US. Gross.
One of the easiest ways that the US could pivot from the current broken two-party system would be to have Instant Runoff Voting. People could both vote their conscience, and vote strategically, without having to compromise their ethics or their country's integrity. What a crazy idea. But, the extremely rich oligarchs who own and operate this country for their own benefit will not allow it, at least without a fight. So they'll continue using their cash and power to lobby to keep the country from adopting the policies that the country actually supports. Like universal healthcare, marijuana legalization, higher minimum wage, ad nauseam.
Recap:
Higher taxes = better constituent service. People expect more because they...have more skin in the game. I hear that conjuring phrase thrown around by conservatives a lot. Yet they want the poor and middle class, who get dick, to pay more taxes, while they want the rich who get almost all of what they want, to pay less taxes. Hilarious. And tragic. And not surprising of right-wing reactionary authoritarianism.
Parliamentarian systems = more accurate representation and accountability to voting citizens who aren't stuck with 1 of 2 choices, and can vote for the best candidate, not just two options that once elected mostly focus on raising cash for re-election.