It's possible for a network to be setup in such a way that Port 443 is forwarded to the Apache machine for online sales and Port 80 is not. Often Port 80 is in use by another application within the network. The online sales will run however this can impact the patrons ability to access the online sales.
The Patron can click on a direct link to the website (https://tickets.yourvenue.org) and reach the online sales site. However, if they try to type tickets.yourvenue.org in the address bar by default the browser will take them to http://tickets.yourvenue.org.
Notice there is no S after the http. The http uses Port 80 to connect to Apache. Apache then redirects the site to httpS://tickets.yourvenue.org/TheatreManager/1/login which then hands the connection over to Port 443 since the link is now using httpS.
It is recommend that Port 80 is also forwarded so that when someone tries to type the address of the online sales site into their browser they are more likely to get to the ticketing site rather then experience errors indicating the site may not be working.
Options for working around a network where Port 80 is already in use are listed below: