Do air carriers assign seats based on customer spending? [closed]

European carriers such as Air France, Norwegian, KLM, etc. charge their economy passengers to select a seat at booking time, resulting in most passengers letting the airline pick for them when they get a boarding pass. You can still change your seat by bothering a gate agent or sometimes on their website, but the selection seems to be limited.

My question is, if you've purchased premium tickets (possibly on a different reservation) will you be more likely to receive a good seat? I can't imagine that it's hard for airlines to rank seat quality, front of plane non-middle seats excluding any limited recline/storage seats.

The reason I ask is because I purchased several one-way tickets within Europe on Norwegian (logged in, using rewards number) and eventually decided to upgrade my long haul flight to premium. The seats I was automatically assigned were pretty mediocre for the flights before I had upgraded my ticket, no middle seats but they were in the middle of the plane which is the worst spot considering Norwegian boards from the front and back. On the flight I checked in for after upgrading, I was immediately assigned a rather good seat, 5th row window. Looking at the seat change options, there's only middle seats and last two rows available for selection so I'm assuming the flight isn't empty. I also didn't do the online check-in as early as I usually do it, perhaps Norwegian already has your seat picked before online check-in opens?

Is this a coincidence or is it Norwegian giving preferential treatment to encourage me to buy premium tickets? Since I only have limited anecdotal evidence I wanted to ask here to see if there's a pattern for Norwegian or other carriers that charge for seat selection.