The hyperlinks to the dates are to the left of the event titles -- I guess people are reading the title and then clicking on the hyperlink after it, rather than before it. Maybe put a border on one of the two columns to better visually separate them?
("intelligence gridlock"... are you choosing your own recaptcha words?)
Some people are dumb ll the time, all people are dumb some of the time. I once ordered plane tickets with the return flight in the wrong month. (Or maybe that was more of a Freudian slip...)
You might hate this idea, but what about a box or some lines delineating each event? Sometimes even obvious organizational cues (like the separate green box for each event on the ordering page) are easy to miss.
On my rather large monitor, there are many times while looking at the calendar that I have a buy tickets link for two or even three different events, with little to no visual separation between the events.
I can easily see someone clicking on the wrong thing, thinking it was the right thing, then just not bothering to read any of the confirmation pages. They shouldn't be blindly ignoring this information, and you are right that they are told the name, date and time of the event multiple times before finally buying the ticket. But, I can kinda-sorta see how it might happen.
Confirmation screens are a BAD thing to rely on. When most people click on a link for something, they'll quickly skim (or outright ignore) text on any subsequent confirmation page because they're confident in the fact that they chose the right link.
Maybe you want to try alternating background-colors with a small black border between columns? Or maybe a visual representation of a calendar?