Delays cost money in every aspect, yes, HOWEVER I'm pretty sure BGT (And every other park for that matter) take this into consideration when building a prototype. Toyota has safety recalls all the time yet is still 1 of the top vehicle manufacturers.........
Another thing to keep in mind is that not all of the delays are due to the ride manufacturer. Some delays are caused by the park and/or their contractors themselves! IE: Crane scheduling, unforeseen building site issues, etc...
Also, Who's to say that BGT wasn't compensated by said party that was responsible for the delay? If I had a contractor that delayed a project but compensated me, why should I be upset?