It would be much better if they just had a streamlined process for charging for larger bags at the airport, and if the fee were roughly the same whether done in advance or not.<p>As it stands, forgetting that Wizz Air requires bags 6cm smaller than easyJet and then getting told you can either pay more than your ticket cost originally or go home, but only sometimes if you get "caught", is just a bit... I dunno, uncivilized, I guess?<p>If you make it say, £15 in advance, £20 at the airport, that is enough to encourage people to do it in advance as long as bags are all checked, you don't need to be punitive.