I understand your point, but there are only X number of seats in an airplane, airline seats are physical products. Why should the same be applicable to a digital product? I mean, it is their property so they are free to charge whatever they want (just like the users are free to leave) but it feels way more intrusive to track users' reading habits and tailor pricing to each user than saying "only 2 seats are left but 5 people are interested, so we're jacking up the price"

It absolutely is a different and more insidious type of dynamic pricing.

First, you can use the airline's strategy to your advantage by planning early. It doesn't feel as unfair because everyone gets the same terms and the system is transparent and equal

WaPos daynamic pricing is simply maximizing value capture, without any way of a consumer benefitting. It's 100% lose-lose for the consumer. You always pay the maximum you are willing to pay. No discounts!

I was just answering OPs question about how airlines were transparent about their system and decided to answer it factually.

while it might feel like a discount, buying airline tickets upfront is not a "true" discount in the traditional sense, because the money is prepaid, and is worth it to the airline to receive guaranteed income from a seat early. A true discount is one where the margins of the product is shrunk to reduce the price.