Speaking as an ex-contestant and phone-a-friend lifeline, what made WWTBAM unique was that it was one of the first shows I can remember where, as long as you were at least 18 and met all eligibility requirements, you could audition for the show from the comfort of your own home via telephone.
I've been a fan of game show for as long as I can remember but, until WWTBAM, I couldn't audition for anything because pretty much every show required you to go to Los Angeles and meet with contestant coordinators, producers, etc. Every once in a while, a show would travel across the country (J!, WOF, TJW/TTD), but you had to hope they were near your hometown. And just because they were didn't mean you would get a looksee. I auditioned for the J! College Tournament in NYC in 1992, and I remember having to write a letter to the show to request an audition, then wait to see if I'd get a response in the mail.
WWTBAM changed the game -- just call the 900 (later 800) number, answer a few Fastest Finger questions and see if you make the next round of phone auditions. If you do, play another round of FFs and wait to see if you get "the call". I probably played the phone game at least 80 times before finally getting through and winning a spot in the "Ring of Fire."
As far as I know, just about every show that wasn't WWTBAM required its contestants to pay their own way to audition or play. Nighttime WWTBAM took care of everything for you -- flight, hotel, meal money, ride to and from the airport, etc. How refreshing it was to not worry about planning a trip on your own, although asking work for a few days off was another story
The show, IMO, also changed the way the major TV networks programmed during the summer. When I was a child, the only shows on the "Big 3/4" networks on the summer were reruns, busted pilots and more reruns. ABC premiered WWTBAM in August 1999 and showed that audiences could flock to TV during the summer. The next summer, CBS unveiled "Survivor". FOX would launch "American Idol" during the summer, and ABC would do the same with "Dancing with the Stars." Each and every time, critics expressed huge doubts that these shows would garner a strong, consistent audience. Each and every time, they were proven wrong.
JD