I was just approving a review where the reviewer talked about the park WiFi being secure and allowing them to do online banking.
I am not sure what they considered secure about the park's WiFi, I would only guess that the park required a username / password for them to connect. This requirement provides you with no additional security, it ONLY helps to limit who can connect to the internet using the park's WiFi.
You can do your online banking using ANY internet connection as long as your bank provides a secure website noted with a lock in your browser and an https:// url. This lock indicates that all the data passed from your browser to the banks website is encrypted and secure. I doubt you can find a bank website that isn't a secure site. I am pretty sure that a secure web site is a basic FDIC requirement for banks today providing any online access.