ADHD

Many ADHD traits are shared with neurotypicals. It's when these things become an issue that most people seek help. Frequency, duration, intensity.

They weren't claiming that people had a habit for paying taxes in general but that because nothing else is a habit they lack the energy to do the things that other people already consider draining when they had to spend so much on things that come naturally and in a way for free to others.

I would argue that brushing your teeth certainly seems to be habitual for most people. It's something they'd do if they went through the bathroom routine in the morning while effectively still asleep. This person is saying that if they don't effectively stand in the bathroom and look at the brush and decide "I will now brush my teeth." they won't do it, where someone else had grabbed the brush while thinking about what they need to get done later in the day.

Depression on the other hand would more likely manifest in a disregard for the necessity of the activity. This person says they do brush their teeth, they want to brush their teeth and they are ready to spend their existing energy on it.

A depressed person often would not be convinced that it matters, nor that they could even make themselves do it if they felt like they had to. Though naturally depression is expressed in many ways, as is any type of neurodivergence. It's hard to put strong labels on these things. Nonetheless it seems sensible to differentiate on these things as most neurodivergence is simply a set of untypical phenomena and behaviour that have collected up enough to start becoming notable.

A person considered completely normal could suffer from the same but simply manage well enough for it to never stick out. No one is entirely normal.

It's very common among autistic people and neurodivergent people in general, it's called executive dysfunction. Essentially your brain has trouble both making and initiating plans. Every time I brush my teeth I have to remember to do it (this is not automatic, all my toothbrush stuff is set up as a visual cue any time I'm near the sink), focus on my task as I go to the bathroom so I don't forget why I went there, remember to take my medicine first so that I don't have to swallow them after brushing my teeth, floss, and brush.

The last two parts sound very simple (and they are, which is why this is so frustrating for many people), but sometimes I will stand in front of the bathroom sink for 5 or 10 minutes, knowing I need to brush my teeth, WANTING to brush my teeth, but it's like whatever 'go juice' neurotypical people have a limitless supply of is just limited for me. Finally after standing there and psyching myself up I can do it, but it does take legitimate effort to initiate the process even if I follow through on all the parts smoothly. I couldn't tell you exactly why this happens even though I can obviously recognize that it is happening, I kind of suspect it has to do with wonky sensory integration problems (common in ADHD and autistic people).

Very few things are true for every person with a given neurodivergence. But this is one of the more (most?) common things that people with ADHD struggle with, some to a lesser, some to a greater extent.