I agree with the others that our robust system of community colleges and commuter universities seems to provide most of what you are asking for.
So I think the holdup is you also want that college or university to be “excellent”. And depending on what that means to you, it is true that may not exist in the United States. But that is almost surely because the extremely stiff competition to be considered an “excellent” college/university in the United States has made it impossible to compete with such a model.
Like, sometimes, unbundled service providers can carve out a market niche by offering lower prices for the more limited set of services they provide. But in this case, colleges/universities competing to be excellent can offer lower prices to their more price-sensitive customers.
Even more so, unbundled service providers can also struggle the most in markets where there are a lot of network efficiencies, not least in what are known as two-way markets where the intermediaries are what are sometimes known as multi-sided platforms:
That’s a pretty good model for “excellent” colleges and universities, where the stakeholders include not just students but faculty, donors, alums, and so on. And to summarize a complex topic, that model of giving price breaks to price-sensitive students/families is likely going to best allow colleges and universities to serve the interests of those other stakeholders.
Like, a common example is college athletics, where a lot of people who do not care about athletics wish there were more “excellent” colleges with little or no athletic program at all. But the usual response is these colleges know from experience that a critical constituency of alums and donors do care about athletics, and so they cannot simply abandon those athletic programs and continue to compete effectively to be an “excellent” college.
So yeah, the way the “excellent” college/university markets work in the US, it is understandable why the unbundled service provider model may not be competitive in that market.
So what about in other countries? Well, just to begin with, other countries largely do not have the same private college/university system at all. Virtually all the other “excellent” universities around the world are some form of public institution, and most don’t actually really rely on, say, donor support the way “excellent” US private colleges/universities do. And then flagship publics in the US want to compete with those private US colleges/universities, and here we are.
But there are a few examples of where donor support does matter outside the US, like the constituent colleges at Oxford and Cambridge. Oh, and look, those are in fact residential colleges closer than normal to the US model. Maybe not so much the athletics, but the other stuff.
Again, from a market analysis perspective, this all makes sense. So if your notion of “excellent” points to the most popular US private colleges and universities, and the publics trying to compete with them, and the most similar non-US universities like Oxbridge . . . it is understandable why your desired unbundled service provider does not exist. It cannot efficiently compete in that sort of market.