Low-cost carriers intend to be low-cost, so in many cases employees work multiple roles. At some airlines flight attendants also work as gate agents or assume other roles (limiting personnel costs). Southwest Airlines is well known for using fuel hedging programs to reduce its overall fuel costs. Check-in at the gate of luggage requires fees, as it requires addition to the weight calculation and last-minute baggage handling.
Online check-in is becoming common, again in the interest of avoiding personnel costs.