Depends on where you are from. In most, if not all, western democracies the Democrats pass as centrist. People like Bernie pass as slightly left of center in Germany for example. And passes as left parties over here would considered full-blown communist in the US.
That's just not true of the Democratic Party by any useful metric and likewise there is nothing about Bernie's platform that would be centre-left anywhere in Europe, the majority of his proposals being to the left of anything implemented anywhere.
If I understood the NYT article correct, the Democrats are put left, among other things, because of support for climate measures. Fun fact, the CSU, as far right as you get in Germany when you ignore the AfD, is also supporting measures to fight climate change now. The CSU also kind of opposes gay marriage, are among the more extremer views regarding abortion. And support public health care. They do not fight to make abortion illegal so. No do they with gay marriage. I see that as them being more "left" than anything I see coming from the GOP at the moment. And the CSU, as I said, considered the most right / conservative of our mainstream parties.
Bernie on the other hand would fit in perfectly well with the SPD, our social democrats. "Die Linke", the leftest one in the article, is a joint party of the SED (the former DDRs government party), some communists from western Germany and the far left wing of the SPD. They are as much left as the AfD is right.
I do see a lot of parallels between the AfD and the right wing of the GOP so. Especially regarding immigrants, muslims, the Covid pandemic and views of family values.
Do you see a situation where the word left means something different if you are talking about national politics versus international politics as a good idea? Because that is the situation you are in if you won't acknowledge that the Democrats are centrist. What then do you call left leaning politics outside the US? Left left? Foreign Left? Communists? This misuse and redefining of words is one of the reasons we have people crying Socialist or Communist of left leaning politicians.
Left and right are relative really. Wanting to shift to a constitutional monarchy was once "the left" or having only Chrisianity as first class citizens in comparison to only Catholicism or Protestantism.
International politics should be contextually anchored essentially. So you say "Party X from country Y is further left than part A from country B." That is putting aside "mixed political aspects". Is a communist country which outlaws homosexuality to the left or right of a free market capitalist country which has gay marriage?
Sure, but in my opinion you should base that on the political leanings of the population of the countrybypu are analyzing, not only on its political parties.
Mixed political aspects are a good argument to be careful in discussing 'overall' political leanings. There are real-world mixups like you describe - for example, Marine Le Pen, while a frighteningly far right extremist on social and foreign policy issues, was to the left of someone like Nancy Pelosi or Hillary Clinton on many economic policy aspects.
Well, personal freedom is neither left nor right but rather up (Libertarianism) versus down (Authoritarian). If you divide the political spectrum in a XY scatter chart you get both Bush, Trump and Obama at Top Right pretty close to each other in Authoritarian Right. Someone like Sanders is to the Left but still pretty Authoritarian in some ways, so not really what is seen as Left outside the US. Someone who is what is normally called Left (left and down) would be Jill Stein (or Noam Chomsky if not only looking at politicians). So in short, both your examples are likely in the Top Right; Right Authoritarians, if they are from the US.
>Wanting to shift to a constitutional monarchy was once "the left"
Yes, in many places they still have names from back then. For example one of the biggest political parties from Denmark is named "Venstre" which literally means "Left", even though they are to the Right (conservative-liberal). Quite funny that a close match from Norway is called "Høyre" which means "Right". They rooted for Joe Biden in the election though and had a big party back when Obama won, because US Left is their Right to center-right and the republicans are just way too extreme for their taste.
It's not, the US left is represented by papers such as Jacobin, intellectuals such as Noam Chomsky, and politicians like Bernie Sanders, (who has only recently - ~last 10 years of his half a century career- joined the Democratic party), and organizations like the Nurses Union.
Sure, it's true that the Democratic Party is to the left of the Republican Party, and that there are actual leftists in the DP, such as Bernie or AOC, but the vast majority of the party is centrist at best, especially on economic issues.
On many economic issues, Hillary Clinton or Nancy Pelosi are on the right of someone like Marine LePen or Viktor Orban.