A (bank) robbery could be played for laughs (Anya's in Him) or as the brilliant solution to a world-destroying problem (Xander stealing the Rocket launcher) but it seems pretty clear that that isn't the case with this one. Unlike Anya's spell-induced lapse this one was clearly successful and has been used to fund plot significant material, unlike Xander's it isn't presented as the innovative response to a specific threat. Buffy herself describes it as her *bad* and while it's also bad to lie to Willow doesn't the fact that she does indicate that she feels guilty about it? Willow doesn't respond by being hurt about being lied to but because the robbery will have created enemies (although she rather suggests that those enemies are not the plain people of Geneva but the kind of capitalist bastards who only value capital).

When Buffy said she was the law in S7 she didn't mean human law, she was using it to explain why she had to punish a vengeance demon's trangressions and she didn't seem happy about it. She still does seem to regard herself as human and while Voll calls her a demon (mother of demon spawn) Sephrellian would appear to agree.