The obedience study is Milgram, not Bandura.
Bandura was with the children in it.
In Milgrams study it wasn't valid due to the reason you mentioned.
Demand characteristics, as they were paid before the experiment, and therefore they may have felt obliged to continue with it.
Also the setting, it was held at a Prestigious University which may have influenced the participant,
and also the experimenter was sitting there, they may also have felt obliged to do this.
The experiment isn't valid because normal people wouldn't shock other people.
However it is RELIAAABLLLEEE