If the defendant had consumed the alcohol just before leaving the bar, their BAC would have been lower at the time they were driving than it would have been an hour later at the station. Thus, they may not have been "driving drunk".

On the other hand, if they had been drinking for some time and stopped just before leaving the bar, then their BAC would have been higher at the time they were driving than when tested at the station. Thus, they would have certainly been over the legal limit and thereby "driving drunk".

Yeah, in this case it wasn’t a blood test but a breathalyzer test, and the major concern was the time between arrest and testing—she might have been sobering up or she might have been absorbing the last drink and she was a few minutes from home. There was no evidence presented that would allow us to know.

0.08 might be too high a limit for sure, I hardly ever drink myself, but that’s the legal limit in Texas.

You’re mistaken — 0.08% is the legal limit in most of the US. And 0.08% corresponds to a moderate level of impairment. Certainly dangerous for driving, but nowhere near “dead drunk”.