Tighter gun control is consistently popular among Americans.
Which Americans and what gun control? I find that while "gun control" is often positively polled, the numbers change drastically when you word precisely what is intended by "gun control". Take these gallup polls for example:
https://news.gallup.com/poll/1645/guns.aspxShould gun policy be more strict? Most Americans answer yes. Then, when asked if they want to ban assault rifles, assault weapons or handguns, the majority say no. In the case of handguns, a whopping +46% say no. Harris supports an assault weapon ban, which automatically puts her on the wrong side of the gun policy polls. Unsurprisingly, this has cost her support.
So is support for LGBT rights
What sort of rights do Democrats protect? What rights do Republicans plan to remove? As far as I understand it, the only strong difference these days is on the T. The majority of people in this Gallup poll answered that changing one's gender is "wrong".
https://news.gallup.com/poll/1651/gay-lesbian-rights.aspxNow, I'm not going to comment on whether it's wrong. What I am noting here is that the majority of people don't like the T in LGBT. Again, this is costing Harris support.
greater taxation of the wealthy
This is correct in a strict sense of "most people support this". However, Gallup notes the following:
"Negligible numbers of Americans mention income or wealth inequality as the most important problem facing the nation. Pew Research noted in reviewing a 2019 poll that few Americans see reducing economic inequality "as a top priority for the federal government to address." And Gallup research conducted in 2018 found the distribution of income and wealth dead last on a list of priorities for the president and Congress."
So, in effect, while people do agree with Democrats on this particular point, they don't care enough to change their vote over other positions.
https://news.gallup.com/opinion/polling-matters/396737/average-american-remains-higher-taxes-rich.aspx abortion rights
This depends entirely on what you mean by "abortion rights". Do the majority of Americans support
some form of abortion? The answer is yes. Do the majority of Americans support the Democrat party's particular flavor of abortion? No.
https://news.gallup.com/poll/1576/abortion.aspxOver a third of Americans want abortion to be illegal entirely. The vast majority of Americans believe abortion should be possible only under "certain circumstances". More specifically, the vast majority of Americans think abortion past the first trimester should be illegal. Right off the bat, the Democrats have to fight over only 70% of voters who want some form of pro-choice. Only 22% of those voters want abortion to be legal under all circumstances. It could very well be that the "pro-choice" voters interested in mild abortion access end up voting for Republicans because they consider no abortion access to be better than a free-for-all.
all positions that Republicans firmly oppose and have indicated they're going to be pushing even further in the opposite direction once they have the power to do so. The last point, abortion, is especially galling when you remember that Trump is responsible for the extremely unpopular Dobbs decision that overturned Roe in a very direct, straightforward way. Trump put three people on the SC, all of whom joined the majority on Dobbs and made up half of it. It is because Trump was elected and put his nominees on the SC that Roe was overturned. Trump is responsible. That's not my opinion; it's what objectively happened. So Americans don't want what Republicans are offering - and yet they keep voting for them anyway.
I think if you took some time to look at the numbers around these positions, you would see that this meme of "people are voting against their own interests" and "people don't vote on policy" simply isn't true. Harris is choosing unpopular policies and losing support for doing so. It's not rocket science.