She's less right to simply do what she always does and ignore how terrified her own children are about things and laugh off the fact that nine year old Liz thinks that wearing eyeglasses means dying alone and forgotten. We know that the poor waif lives in a hellish mindscape because idiot parents assume everything is by definition fine because what does a kid have to freak out about. This belief in childhood cheerfulness and obliviousness is what informs her angry screaming about negligent monster children who selfishly want their poor injured mothers to go broke so they can be careless. It's also why Elly dragged her feet on contact lenses like an idiot: Liz would always be losing them because reasons.
The reason that I mention this is that Michael impresses me as being somebody with ADHD who slipped through the cracks because no one is paying attention. All Elly sees is someone faking a total inability to do basic arithmetic so he can run around stupidly because the alternative is horrifying and scary. If he were to be diagnosed later in life, she wouldn't be upset about all of the missed opportunities and remorseful about punishing him unfairly. Anyone who knows her would know that she'd be all about screaming about how everything bad happens to her and how everyone wants to blame her for giving birth to a defective kid. The damage to him can't matter because she's damaged more.