[eroded]

s/complementary/complimentary

This is a fairly edge case, that only really occurs on US domestic flights. The majority of the world's frequent-flyer programmes do not give space-available upgrades in the way that say American or United do domestically.

The vast majority of those travelling in premium cabins (or their employers) paid cash for their ticket.

[davewasthere]

Admittedly my airline experience is not with US airlines, but space-available upgrades for our valued frequent fliers are very common in the rest of the world.

[eroded]

Care to give an example? I am not aware of a single programme outside of the US that offers this.

[driverdan]

You're right, there aren't automatic upgrades on most international flights for those with status. But a lot of people who fly international 1st / business are doing so on redemptions.

[reeses]

It was an oft-quoted meme in the 80s and 90s (and possibly earlier) that all the seats on flights from the continental US to Hawai'i were reward travel.