Fuel surcharges don’t matter much to most consumers. They’re advertised as part of the paid fare when buying a ticket. They even earn credit in revenue-based frequent flyer programs. They really only matter to consumers who have airfare discounts that don’t apply to the surcharges, and to frequent flyers booking awards.
Since fuel prices have dropped, and fuel surcharges are now absurd on their face, several airlines have just renamed ‘fuel surcharges’ as ‘carrier-imposed surcharges’. In the US that’s important because in the US fuel surcharges unrelated to the price of fuel are considered by the DOT to be illegal.
Now there’s literally no justification for the surcharges. They’re just a fee for nothing. They’re ‘carrier-imposed’ (of course, who else sets fares?) but don’t cover anything in particular. That begs the question, why do airlines do this?