1) Yes, this is a fuel surcharge.
2) The fuel surcharge has nothing to do with why your ticket is more expensive than last year.
3) The fuel surcharge has nothing to do with why a ticket on carrier A is more expensive than on carrier B.
4) UA most certainly does have a fuel surcharge for LAX-AMS itineraries. It may not be separately broken out on every website, but it is most certainly published in the fare. Here is the full fare construction for a random UA fare for LAX-AMS-LAX in December (14 to 21):
Fare 1: Carrier UA KLXNC13S LAX to AMS (rules)
Passenger type ADT, round trip fare, booking code K
Covers LAX-IAH (Coach), IAH-AMS (Coach)
$120.00
Fare 2: Carrier UA VLX3RCE AMS to LAX (rules)
Passenger type ADT, round trip fare, booking code V
Covers AMS-EWR (Coach), EWR-LAX (Coach)
$436.00
UA YQ surcharge (YQ) $420.00
US International Departure Tax (US) $16.30
US September 11th Security Fee (AY) $7.50
US Passenger Facility Charge (XF) $12.00
USDA APHIS Fee (XA) $5.00
US Immigration Fee (XY) $7.00
US Customs Fee (YC) $5.50
The Netherlands Passenger Service Charge (RN) $20.70
The Netherlands Noise Isolation Charge (VV) $2.80
The Netherlands Security Service Charge (CJ) $17.70
US International Arrival Tax (US) $16.30
Subtotal per passenger $1,086.80
Number of passengers x1
TOTAL AIRFARE & TAXES $1,086.80
For the same dates, AA and DL also carry a $420 YQ. US does not separately break out YQ. All 4 carriers are in the same rough price range.
If ever there was a tempest in a teapot, it is the concern over YQ surcharges on revenue tickets.