Usually the reason you don't see flat rides commonly appearing at fairs (like Boosters let's say) is because of their dire throughput and design to be transported rather than permanent (see Samurai)...
Tbh, fairs are fairs, and whilst their rides are run faster, it's because they are temporary fixtures... Theme parks must think long term, and as such, cannot afford to run rides at extreme speeds and long settings, otherwise they'd potentially break after a while and become a maintenace burden (like Samurai)...
Look at how Blackpool had both a Zierer Starshape and two (to make up for lack of throughput) Fabbri Boosters, both are now gone (though Bling suffered from the closure of the South Entrance in my opinion more), which goes to show that not all flat rides would be successful in a theme park environment just because they are good at the fair circuit... Two different parts of the same industry...