Virtue doesn't scale. Hence taxes for public good stuff because otherwise only the town with a generous Moneybags would have roads or a fire service (and the town with a racist Moneybags would only have a fire service in the white quarter). It's also hard to coordinate - see disaster response.

We're talking simply about charity. There are plenty of wealthy liberals - like Hollywood, Gates, Buffet, Silicon Valley, etc. All the people who donated to Sanders. Plenty of money to give to charity.

Resources are unevenly distributed. Like, why don't the homeless all just pool their resources and buy a house?

Seattle votes heavily Democrat. There's only a tiny fraction of them in Seattle that are homeless.

It's an extreme illustration of a principle that holds at many different levels.

Agreed on both of your points.