Same happening at parking garages these days, the operators force their clients to use a proprietary payment app and have pretty much stopped to install/provide the cash/credit card machines at the exit...
I did get taken for about $45 about a year ago trying to log into an app to pay for parking, funny thing there was that, at the moment of payment, it clicked and I realized it. I just stopped eveything and called my cc isuer and said I just got hosed. They said after a bit of verification that, yup, you got hosed, for $45. They resolved it and there was no problem, but the lesson was clear.
In this particular instance, I think I jumped the gun; I did get the prompt to log in as new user at the other site, but that might have to do with it not seeing my mac address in some time. I did get a specific advertisement attachment each time though, which I never used to get [any]. Anyway I made a post and got good feedback from a couple members on that site so all seems good.
[added] then, when I returned to that location and had to pay for parking, I let my office handle it and they initially had problems reaching the legitimate site through the information super garbageway.