I haven't got a clue what people think about it. I guess someone could think that because I apologize for them bumping into me, I don't mean my apology when I apologize for losing my temper or being unkind or something. That just seems awfully... strange?
When behavior is examined on a sociological level, it often doesn't make a lot of sense or seems counter-intuitive on a personal level.
Looking at the paper I posted, the thing to take away from it is not "the more you, personally, apologize, the less people will believe you are sincere," but rather, "because we belong to a segment of the population that is expected to behave a particular way, people are more likely to assume we're only following social guidelines and not behaving sincerely."
As with a lot of social phenomenon, people don't necessarily realize they're doing it, likely aren't doing it consciously or purposefully, but we reach these conclusions by comparing data points (why are people more likely to say that they expected an apology from women? Why are people more likely to say that apologies from women are less sincere?) and trying to make sense of them.