We have 'em here in Wisconsin all the time, often referred to as a "fishoree" or "jamboree". No real big money events, at least not over a few hundred bucks for the first few places.
Most are just high profile social events that provide an excuse to eat, drink and fish (some folks actually do that). Usually lots of nice door prizes as well. Often run by a local tavern that counts on the crowd to patronize following the event to make their end.
Mobility is still an issue. Use your imagination that puts a few hundred anglers with their shacks, trucks and other attendant paraphernalia on a 250 acre lake............ Not much wiggle room save for the initial area you were able to stake out. Naturally, community spots are mob scenes........... Larger waters offer some more options but you gotta know the water.
/m