[Bruxley]

Are these businesses somehow less public than a college campus?

Most definitely. A retail, or any other business, is open to the public, but isn't a 'public place'. In other words a singular purpose exists, to do the business they are in, that's it. They are not open for use by the general public. They are not for 'use by the general public' they are there specifically, and singularly to sell their wares or services.

Campuses are more like small towns then shops. There are a wide variety of public uses going on and although certain building may be closed, a campus is perpetually open to the general public even between semesters when no classes are held.

Here is the analogy that the SCOTUS used in the Marsh case cited above:

Ownership does not always mean absolute dominion. The more an owner, for his advantage, opens up his property for use by the public in general, the more do his rights become circumscribed by the statutory and constitutional rights of those who use it. Cf. Republic Aviation Corp. v. N.L.R.B., 324 U.S. 793 , 65 S.Ct. 982, 985, 987, note 8, 157 A.L.R. 1081. Thus, the owners of privately held bridges, ferries, turnpikes and railroads may not operate them as freely as a farmer does his farm. Since these facilities are built and operated primarily to benefit the public and since their operation is essentially a public function, it is subject to state regulation. 3 And, though the issue is not directly analogous to the on before us we do want to point out by way of illustration that such regulation may not result in an operation of these facilities, even by privately owned companies, which unconstitutionally interferes with and discriminates against interstate commerce. Port Richmond & Bergen Point Ferry Co. v. Board of Chosen Freeholders of Hudson County, supra, 234 U.S. at page 326, 34 S.Ct. at page 823, and cases cited, 234 U.S. at pages 328, 329, 34 S. Ct. at pages 824, 825; cf. South Carolina State Highway Department v. Barnwell Brothers, 303 U.S. 177, 625 , 58 S.Ct. 510. Had the corporation here owned the segment of the four-lane highway which runs parallel to the 'business block' and operated the same under a State franchise, doubtless no one would have seriously contended that the corporation's property interest in the highway gave it power to obstruct through traffic or to discriminate against interstate commerce. See [326 U.S. 501, 507] County Commissioners v. Chandler, 96 U.S. 205 , 208; Donovan v. Pennsylvania Co., supra, 199 U.S. at page 294, 26 S.Ct. at page 94; Covington Drawbridge Co. v. Shepherd, 21 How. 112, 125. And even had there been no express franchise but mere acquiescence by the State in the corporation's use of its property as a segment of the four-lane highway, operation of all the highway, including the segment owned by the corporation, would still have been performance of a public function and discrimination would certainly have been illegal. 4


We do not think it makes any significant constitutional difference as to the relationship between the rights of the owner and those of the public that here the State, instead of permitting the corporation to operate a highway, permitted it to use its property as a town, operate a 'business block' in the town and a street and sidewalk on that business block.

In short, when they became open for general public use they distinguished themselves from a private home owner or place of business.