Even among state universities access to electronic journals for guests is becoming increasingly rare (usually prohibited in the license agreement). Also if you look to much into how scholarly communications works, the idea of charging 50k is insane since that vast majority of the cost of journals are actually paid for by universities in the first place.

edit: although I do agree with your point that in with the current state of things the cost per usage of JSTOR is significantly less than most other electronic journal collections

I would be impressed if it's an actual trend that guests were being blocked from accessing licensed content.

I work in this field and I can say that almost all databases and journals have IP authentication, generally with the entire campus IP range white listed. If the vendors don't implement that, they generally use password protected accounts. There are some alternatives such as uploading a list of barcodes, Referring URLs (I'm not kidding ProQuest for example allows this), Athens, Shibboleth, and a few others. These, however, are not commonly implemented by libraries because they are not widely adopted by vendors and require additional IT support that libraries simply don't have.

Therefore, unless libraries proxy all their users through their proxy servers (They don't for on-campus users. Usually, all links will go through the proxy, but if on campus the proxy will redirect you directly to the database to avoid the overhead), it would be near impossible to enforce the restriction of guests. I would wager that in many of these scenarios, it's all smoke and mirrors, and that access is really there if you know what you're doing (e.g. just visit the vendor site while on-campus without going through the library links).

I've been at at least one university (a smallish liberal-arts college) that used a separate foo_guest wifi network for guests, which dumped people into an IP range that wasn't in the database-access whitelist (enrolled students and faculty would connect to a different wifi network, using their username/password, that was whitelisted). I agree that that isn't usual practice, though, despite being technically required by some database agreements.

The configuration I've seen is to have not only guest accounts but also to have guest computers which are on a separate IP range, same with the guest wireless network. The important issue is actually what do the details of your license agreement say regarding guest users. Some state universities will actually request for this to specifically allowed since in many states it's considered, even if unofficially, a right of tax payers to have access if they need it

But many state schools let you join the library even if you're not a student. e.g. http://www.lib.iastate.edu/info/6197 - $20/year for a non-affiliated member.

ISU's extramural borrower card doesn't allow holders remote access to (paid) academic databases.