The phrase "saver seats" refers to specific seats or areas in a place, like a theater or cinema, that people save or reserve in advance for themselves or others. Full definition
You can certainly find the «saver» business and first class seats, so it isn't limited to economy, but you do have to find saver seats. (richmondsavers.com)
In general, the cheap level 1 saver seats go fast and can be hard to find. (rewardexpert.com)
And although we value most airline miles over 1 cent each, that's mainly based on being able to find premium cabin saver seats. (thepointsguy.com)