And theme parks don't have months of being packed solid between the hours of 9-6 (possibly longer at late notice)?
I think it's more a lot of people here are comparing the role of ride host to the wrong things... It's an unique role as it features so many different aspects (guest interaction, safety, throughput focus, etc) which when a park is at full capacity of guests angry as they keep having to queue for rides and what-not, it's not a role for the light-hearted...
What mentality? Some of us are stating that ride staff work excessively hard for long extended periods of time over the March-November season... Closing a park at 11pm would not be beneficial to those younger staff members (as mentioned, UK parks hire a LOAD of young seasonals) if they have to hang around in an area which isn't the easiest to travel to (I doubt many buses run after 11pm, or trains) car aside...
Having experienced Chessie at high numbers (18k odd a few times), it's near as damn akin to Christmas shopping busyness... And lasts for two months as well...