That alone is distracting enough for me. I hate the "look busy" vs. actually being busy game people play in offices.
I have severe ADHD and I don't even know what discipline feels like. That's precisely why I can't work in offices. In fact, other people are more productive when I am not in an office with them as well.
I'm cursed with the fact that a lot of my hyperactivity manifests as talking. It's actually problematic enough that I have been reprimanded for talking excessively at points in my past. I am quite charismatic too, so people end up getting locked in these hour+ long conversations with me lol.
At home, there is no one talk to but my significant other who often works during the same time. So, WFH skyrocketed my productivity. I go in the office two days a week, and I basically lose two days of work a week now.
I've been WFH since 2016 and I never had an issue with focus when doing paid work. I do want to get paid.
YMMV. When I was freelancing, I charged by the hour. Working for 2-3 hours per day was just enough to keep me and the family afloat with some extra money to spare. I haven't saved a penny in 5+ years and haven't had any money for a downpayment on the apartment we were supposed to buy.
Unfortunately, switching to per-project payments would be terrible for me. The deadline would be too far into the future for me to feel the danger of failing the project.
For an undisciplined person anything can be distracting: birds chirping, picking up a delivery, cooking, a friend dropping by, daily chores like washing, organizing things, etc... it's an endless list really.