I see that no-one has mentioned money. Some events build expenses for their volunteers into their calculations, others don't.
I've taken the view that volunteering for events is payback for the unpaid work that enabled the events I rode. I have had expenses for filming and editing for a small number of events, for which I'm very appreciative, but in general I've been giving my time and money to help develop Audax.
Curiously, the events I generally rode had fairly focused volunteer support. Chris Crossland's Two and Three Coasts 600km rides were one example of that. The Depart/ Arrivee was also the sleep control, and volunteers came from the CTC groups of the immediate area. The amount of travel involved for volunteers was minimal, there were volunteers at Glasson Dock, and I don't know if they were local.
My involvement with Andy Corless's rides was a bit more complex. I wouldn't have entered them, as they're too hilly for my tastes. But hills are easy to film, and the scenery looks good, so I was getting a lot out of following them. However, the Langwathby control on the Pendle 600 was pretty remote, with no real chance of local involvement, so I tended to end up involved in cooking activities. The same happened on the first Mille Pennines.
I've also seen how LEL volunteering has evolved, as my partner Heather ran a control in 2001, 2005, 2009, 2013 and 2017. She relied on friends and family initially, but as the event has grown, volunteers have been recruited from around the world, mainly thanks to Danial. That has considerable cost implications.
So I'd see helping at events as a very varied phenomenon. Some are doing it for the satisfactions it gives them. Some are helping to develop the activities of the club they belong to, some are helping friends and family. While others are involved in a sort of cultural exchange.
Underlying those differences are a variety of monetary arrangements, some organisers provide expenses, some don't. To add a layer of complexity, events vary in remoteness, so local volunteers are hard to come by. On top of all that, there is no cross-subsidy between organisers.