In the UK where this ticket is from, if you buy a ticket from the machine in the station it will spit it out in potentially multiple parts (because one isn't enough space for all the information)
You can see this ticket says "Valid only with Travel Ticket", which means this is the second of two parts. The "Travel Ticket" (not pictured) is the one that actually allows you to travel on the train, and the seat reservation part (pictured) is the one that gives you a seat.
Normally the machine only gives what you need, so if there is no seat reservation you'll get the travel ticket only.
So the mystery isn't that there is no reserved seat, but that because there is no seat, this ticket doesn't even need to exist. The machine could have just not printed this ticket at all.