I recently bought a ticket from a (legit) European airline, with which I had flown before, for a national flight in an EU country.
In the process of booking, as I normally do, I tried to find the cheapest option and noticed something I did not think was possible. For the same exact flight, looking from two different tabs in my browser (one in which I was logged in to the airline system, one in which I was not), the price of the luggage option was significantly different (around 12 euros out of 25; the price of the flight was instead the same).
I believe that in my case this happened as I had to book this exact flight for my parents first, and then book it for myself, yet I am still not sure if the airline is allowed to do this.
Therefore my question is: is it legal for an airline to show different prices for the same flight to different customers at the same exact time? Please note that I am explicitly referring to showing the prices at the same time, since I know that at different times of the day/week prices can be different.
P.S. I read this and this but I do not think they address my question. Moreover, I can say that after logging in from the browser tab where I was not logged in yet (I had to to make the purchase), the price shown was updated (and increased).
EDIT To clarify, the higher price was the one shown in the tab in which I was logged in. I had bought the ticket for my parents the day before, and my suspicion is that the airline increased the price because they "knew" I might be interested in that flight, given that I had already booked some seats, even though this time I was buying a ticket for another person.