I don't mind event rides and have enjoyed several in the past, especially the Rosarito (Tijuana) to Ensenada, and Mexicali to San Felipe rides. Our club rode mostly together and had one or two sag wagons so we didn't need any support from the organizers, if there was any support. Mostly we appreciated the Mexican law enforcement folks for traffic safety.
My gripe about "charity" rides is they're a weird mix of purpose and participants. They're financially inefficient for fund raising (it's more efficient to just donate money directly to the organization), and mostly done to enhance public relations visibility.
And a common complaint is the wannabe racers scare the crap out of the slowpokes who get an early start so they'll finish before dark. Yeah, the roadies will fuss at the slowpokes to wait for the racers to start first so there's little risk of an 8 mph cruiser in a reverie being buzz passed by a paceline. But that also thwarts the goals of the early bird slowpokes who need the early start to finish on time.
I've heard some casual riders say that when they did as suggested and started later to minimize being passed, they were basically abandoned, without traffic indicators to notify them of upcoming turns, etc.
For some reason the non-charity type event rides seem to handle these big rides more effectively. I haven't heard many complaints about lack of food, direction guides, sag or toilets.
I suspect that's due in part to the way these rides are inspired and organized. A lot of charity fundraising stuff is contracted out to marketing specialists who may have little or no interest in cycling. So unless they consult with experienced cyclists they're bound to get some things wrong.
The non-charity type event rides usually were started by cycling enthusiasts who have a better idea of how to make these rides more successful as cycling events rather than as fundraisers for charity.
When I want to support a favorite local organization I just send money. I rarely if ever participate in their events. Same with holiday food drives. Unless we're donating directly to a needy family, food is inefficient. Charities that help feed needy folks need money, not food. They have dietitians and purchasing agents who can save money buying in bulk and arrange their own inventory management. Direct donations of food shift a lot of burden of physically organizing inventory to agencies that are operating on minimal staff. Some friends do holiday food drive rides, and occasionally I'll tag along. But I don't usually pick up food and carry it around on the bike to donation stations. I donate food directly to neighbors or homeless folks I see along the streets where I ride.