In the US. they cannot get enough people to use public transport to make it profitable, so it does not happen and the process is self-reinforcing as the lack of quality public transport. However, I am imagining that placing social housing units in transport hubs like subways, bus stations, train stations, or maybe even airports would encourage people to use other forms of transport besides cars, and also help the economically disadvantaged people to access the forms of transport literally outside their front doorstep. The ideal layout I imagine is large hexagonal food courts with passages to subways or whatever transport is present in the area, or exits to the surface.
At first I thought subways should have entrances at the top and trains at the bottom with housing in multiple floors in-between, but I realize now that is likely to cause inconvenience for those trying to use the subway without living there. The subway should have a hexagonal food court or hub with shops and services, and the social housing should be on floors above it with balconies looking down and some kind of glass ceiling at the top to allow sunlight in, maybe with some kind of greenery or art in the center at the bottom level.
Crime may be an issue, but police are typically located in these areas. However, police brutality or community mistrust of law enforcement can also negatively impact satisfaction of those living in transport hubs, who may feel they are always being watched. The large amount of people and witnesses that can see the subway from their units is likely to discourage more serious crime, but property crime and vandalism would probably happen often just like in other high-traffic places. The large amount of traffic through the hub where people are living may also negatively affect their satisfaction there, but it would be similar to a big city and they would normally be above all of the higher traffic areas which makes this issue less severe. People who are not used to city environments may be intimidated or less comfortable in a housing project like this, but it would be better for the planet, public transport, and it can help the issue of homelessness. This ideas also assumes construction of a new subway or transit facility designed for living, not the currently existing ones.