I booked a 'Basic Fare' with Porter Airlines. I arrived early for my return flight from MDW to YTZ so I tried to get onto the earlier flight. There was space, including when I checked AFTER everybody had boarded. However, they wanted $150 extra to allow me to fly standby. I declined.

I just don't understand the logic from their perspective. They had empty seats they could have filled. My flight was completely full so people may have been bumped or at the very least they couldn't allow people to fly standby. Why wouldn't they want to fill their seats by moving people onto earlier flights if possible?

Air Canada has always allowed me to standby for free so unsure if this is normal?