Something which I've been wondering for some time now:

I've noticed the websites of several airlines like UA and CO feature seatmaps for all individual flights so pax can select the seat of their choice right away when booking their ticket, whereas many other airlines only allow ticket holders to pick their seat of choice 24 hours prior to departure, during the online check-in process.

Now, my question is: can pax also somehow book a ticket on CO or UA without selecting a seat (or be given one randomly by the system)? Because if they can't, then those seatmaps are actually a fairly accurate and up-to-date outlook on the total load of each flight and definitely a great tool for non-rev travellers to check the loads.

What do you all think? Are all pax given a seat by the sytem randomly, in case they haven't selected one themselves?