The first, of course, is that people are supposed to bend over backwards to compensate for her inattention, lack of awareness and general ditziness. She proved that at the bank when she complained that the tellers were put on this Earth to do whatever she wanted and she proved it again when a department store clerk interrupted her ranting about how unprofessional she was by pointing out that Elly was guilty of the same things she'd accused her of.
An allied behavioral anomaly is the assumption that people in the service industry are somehow obliged to look after the offsprings while she goes and does whatever. As the "Storm in April" special reminded us, part of the reason Elly was so angered by April's wandering around is that the bossy people she used to work with pointed her to an unfair and mean sign that said that they are not babysitters for idiots.
This leads me to the most annoying part of Elly's struggles with the service industry: her playing at being a store-owner. Most of the people she'd imposed on can deal with her nonsense with, if not aplomb, then at least enough professionalism to avoid screaming in rage; the merest refusal to acknowledge how awesome she is, on the other hand, brings out the easily-infuriated asshole in her.