There have been a lot of incarnations of "roller derby" since it's development in the 1920's. During the 1980's and 1990's there were two attempts to televise skating. These were RollerGames (https://en.wikipedia.org/wiki/RollerGames) and RollerJam (https://en.wikipedia.org/wiki/RollerJam). Although both shows had some great skaters and athletes in their line-ups, neither show can be described as televising an actual sporting event whose outcome is unknown and where the plays are unscripted.
The Texas Rollergirls (https://en.wikipedia.org/wiki/Texas_Rollergirls) organized in 2003 and that event is regarded as the birth of modern roller derby. The biggest difference between the Texas Rollergirls organization and the earlier attempts to promote roller derby relates to the ownership of the organization. The athletes of the Texas Rollergirls very quickly decided that ensuring their new sport remained a sport was to ensure that their league was athlete owned. (Rollergirl: Totally True Tales from the Track covers that learning experience.)
Of course, any team sport requires more than one team. Other cities formed leagues. In 2004, the forerunner of the Women's Flat Track Derby Association was organized. (https://wftda.com/history) It was really a message board/forum. Twenty of the leagues that participated in it formally organized in 2005. WFTDA is 503c non-profit which sets the rules and regulations for play, sanctions games, and basically does all the kinds of things that other minor sport associations do. Around 2010 (I'm not sure of the date) Modern Athletic Derby Endeavor organized. Basically, M.A.D.E. offers a different rule set that tries to maintain the speed that the banked track provided. It's an alternative organization for those leagues who may not fit WFTDA or who want to go in a different direction.
The short answer to your questions is that the televised skating athletic events of the 1980's and 90's were very akin to the WWE. They showcased talented athletes, but were partially to fully scripted.
Since 2003, flat track roller derby under both the WFTDA rule set and the MADE rule set is a 'real' sport. As a minor sport, inter-league play does struggle to have games with parity. Athletes play where they live. So a team that draws from a small city has a lot less breadth and therefore depth than a team that draws from a major metro area. (Check out flattrackstats.com for some examples of disparity.) Since all players (myself included) pay to play in dues and rink time and equipment there is no impetus not to play to win every single game.
It's sort of like comparing the WWE to high school wrestling.
