does it pay to win a penny for another airline's banner
Having spent and earnt money through Google, let me tell you it is much more than one penny.
Chances are, as Ryanair's content is highly relevant, an out click from the home page will cost anything upto €1. Norwegian would then have to gain more than Ryanair would lose - and Ryanair's usual bluster about being cheapest would mean they'd expect to win, let's say 3 in 4 pax on any head to head route. Yet Grenoble, advertised in Norwegian isn't head to head anyway - or was the surfer in question in Norway at the time?
Google is going to take about 1/3 of the revenue, and Ryanair will get the rest (
afaik, 30% is typical, Ryanair will get a bit more) - so as long as Ryanair's "loss" of business is less than Norwegian's "gain" + the Google margin, Ryanair are still quids in.
Except - and here's the clincher? Did I hear you say Norwegian radio were wondering about this? Now would this be a commercial station, or the NRK, from whom such publicity cannot be bought? Repeat such a conversation across dining tables and in forums like these.
I'd say FR's webmasters know exactly who they can ban, but are quite happy to let it run. After all in the UK now, I get adverts for Eurotunnel - are they not an indirect competitor too?