Small retail shops.

Huge retail shops (Wallmarts/Targets).

Non-profit retail (Goodwill).

Restaurants (Coffee shops, family restaurants, Olive Gardens)

Utility buildings. Utility Workers.

Housing; low- medium- high- and no income. Plus some for the 0.01%.

Schools; Pre- elementary- middle- high-schools and College.

Office space.

Pools.

Gyms.

Hospitals.

Doctor offices.

Animal shelters.

Green spaces.

Cinemas.

Amusement parks.

Fire departments.

Police departments.

Community centers.

Jails.

Courthouses.

City/County/State/Country centers.

Temporary housing (From hotels to short-term rentals)

Commercial shipping (by rail, road, and sea)

Car storage (travel between distant cities)

And perhaps most importantly, competition (that is, alternatives) for all of the above; since campuses tend to be monopolies for many offerings.

Notably, many college campuses seem to offer most of these services already: food courts restaurants, and cantinas, small retail for student and faculty needs, utility buildings, housing (undergraduate and graduate, including for students with families), childcare centers for the children of students and faculty, office space (duh), gyms and pools (which HN is fond of ranting at), access to medical services, green spaces, campus fire and police, and park-like green space around campus, and competing services in many of these categories located just off campus.

Speaking for myself, I've never seen a campus with all of: A full grocery store. Elementary, middle, or high schools (with associated sports facilities). Jails. Courthouses. Hospitals (not basic medical services, fully featured hospitals with Ambulance support). Police forces (not half a dozen campus cops, or loaned police officers)... and so forth.

And remember, we're discussing building cities like campuses - there is no "just off campus" space available for competition.

We're discussing campuses the size of Manhattan Island, without most of the roads (which will hugely impact the ability to deliver goods and take away waste; just see how New York is taken over by these two activities at night). Also, without suburbs, so the housing (and all of the support necessary for that population) needs to be that much more dense (and affordable).

I think it's interesting that your list omits industry/manufacturing/construction, typically very space- and vehicle-intensive. Industry is no longer a part of the urban core of a lot of cities in the west (and it can have significant negative externalities for the folks living around it), but it really needs to be solved in order to reduce car dependence.

It just didn't cross my mind; a side effect of the city I live in being a campus town, not a manufacturing town.

You're absolutely right - manufacturing needs to be solved.

I'm interested to find out what makes these groups so different that being a walkable area is incompatible between them.

i'll take a stab at what the author of that comment might have meant - how I understood it at least

there are 2 ways you can define "walkable"

1. it is physically possible to walk there - e.g. there are paved sidewalks

2. it is convenient to walk from the place you are to the place you need to be

i think that the misunderstanding here might be that you and the comment above are thinking about 1 while the problem is actually 2

to pull a quote from the article:

"students who live in dormitories are able to work, eat and worship all within walking distance of their homes"

there's also a link to this concept of a "15 minute neighborhood"[1] where everyone can walk to their basic daily needs w/in 15 minutes, or beautifully summarized as “Put the stuff closer together so it's easier to get to the stuff.”

so the proposed problem is that the set of things w/in that "daily needs" category, AKA the "stuff", might grow, due to the increasing diversity of the population you're servicing, to a point where its not possible to give that to everyone

[1]https://www.strongtowns.org/journal/2019/9/6/7-rules-for-cre...