Capitol Heights is an interesting example to choose. It's a predominantly black neighborhood that is still pretty dense (5000 people per square meter, 2000 people per square km), at least compared to national averages or even the averages in the same metropolitan area.

By some metrics, it's more walkable than average in the DC area.

I do feel like it's a bit cherry picked, in that you've included a major park (Marvin Gaye Recreation Area), serviced by a major biking/hiking trail, in the satellite image, and it's the most central station on its line to have parking, as the system kinda switches emphasis from an urban transit system in the center to a suburban park and ride/commuter rail on the edges. The fact that the DC Metro does both is kinda a controversial design choice, but it was intentionally designed to serve the suburbs, too.

There's stuff that can be done. For whatever reason, Maryland left huge swaths of its boundary with DC as a big green trail, but didn't fully develop them as parks or tree-lined spaces. And the homes that were built there about 100 years ago aren't as nice as some other neighborhoods in the DC region. And the whole area east of the Anacostia river is a bit less economically developed than the center and west and north of DC, with a complicated history of race and infrastructure and development.

I'm not entirely sure the current residents would welcome multifamily residential or mixed use developers with open arms, but the demographics and politics and economics and history of that neighborhood isn't one I'm very familiar with.

I like talking zoning and land use, and encouraging density. This particular example is one that I don't think is as simple as OP suggests.

Imagine an entire neighbourhood near there with bike lots, and bicycle lanes....

Where I live, they operate a city bus system as a tax write-off or something equally sketchy. You never see the buses. Maybe once in a blue moon. Maybe there’s just one? There are a few bus shelters but they don’t really have them in residential areas. So I guess you can get around downtown but in no way, shape, or form is it meant to replace personal vehicles. I don’t even know why they bother, unless it’s like a tax cheat.

You must think how it would affect those 30 homeowners if their quality of life was altered by having density in their "peaceful" neighborhoods. Have you people ever considered how much the traffic would increase for those poor homeowners who already fear so much? Now you're trying to change their whole neighborhood, this is America! We can't have change here! It's been this way since America was America God damn it!

The one large field looks like park/playground, which is kinda what you want? What’s your issue with this picture exactly? It’s not massively high density?

Residential neighborhoods need Infrastructure too.