The Transport Secretary has accepted that the ticketing system on Britain's railways is "complicated" after it emerged that some fares will cost up to 48% more under a new payment method.
Patrick McLoughlin said improvements are needed across the country after acceptance of payment by Oyster and contactless cards from central London was extended to Gatwick Airport.
Analysis of fares found that some passengers going to the West Sussex airport are being charged more if they tap their cards on the barriers rather than queue up for a ticket.
Holidaymakers and business travellers buying a paper ticket from London Victoria for a return within one month using the non-stop Gatwick Express service pay £34.90.
But anyone who uses Oyster or contactless will be charged 13% more as the journey is billed as two £19.80 singles.
The increase is even more significant for people returning from the airport on the same day. A day return paper ticket costs £26.70, meaning those who switch to the new payment method will be charged 48% more for the same journey.
Speaking on a visit to the airport, Mr McLoughlin said: "The ticketing system in our country is complicated and we need to see improvements being made in it. I'm the first to accept that.
"But what I'm also wanting to see - and what today is an important marker of - is expanding systems which people understand (and) are used to using."
He told reporters there are "other ways down here than just the Gatwick Express" and insisted that "on most journeys it will be cheaper" to use contactless than buy a paper ticket.
Mr McLoughlin added: "It's not just about price, it's about convenience, it's about making sure we get the best use of mechanisations on new ticketing systems."
Passengers are being advised to research the various payment methods and types of fare ahead of their journey.
The new system means travellers no longer have to use a different payment method to get to the airport than they do for Tube and bus journeys in the capital.
Five other stations along the route - Horley, Salfords, Earlswood, Redhill and Merstham - have also been added to the network.
The Department for Transport said the technology would provide "vastly more convenient journeys for passengers and will help reduce overcrowding at stations".
Contactless payments were first introduced on London buses in December 2012 and the technology was rolled out in September 2014 to include the Tube, tram, DLR, London Overground and most National Rail services.