I can honestly see somebody not knowing that they had to pay property taxes on a plane. You don’t pay property taxes on a car and you don’t typically live in a plane.
I’d chalk this up to her accountant being negligent and the airport she kept it in also being negligent.
In Missouri, a tax on cars, boats and airplanes is collected every year.
Depends on what state you live in, and in her case being a long time state political parasite, she was aware of the tax. I can almost believe she thought the hired help was taking care of it but I would bet that she went a few years skipping the tax and decided that if they don't ask, she wouldn't tell. It's always easier to ask for forgiveness than permission. ;~))