There were few surveillances in the Compaq Building.
There were a few cameras on the first floor, but almost none on the second, and by the third floor, there were no cameras at all.
The reason is simple: a headquarters engaged in illegal business would never install too many cameras, even if they don't consider what evidence the cameras might capture against them, there's also the potential hacker intrusion to consider.
Illegal is illegal; even if it's the FBI's black operations, they wouldn't be blatantly obvious about it.
Americans may not understand the Chinese idiom 'disaster within', but they do understand the concept very well.
So, there wasn't a monitoring room on the third floor that could see every corner; they had to rely on human eyes to know what was happening below.
But Gao Yi and his team didn't know this, they overestimated the hardware facilities of the Compaq Building.
