it's Jet2.com because someone else has the rights to the Jet2 brand name
I agree it doesn't make a blind bit of difference but the statement above is incorrect. If you check via the Intellectual Property Office (
www.ipo.gov.uk) then you can see that Jet2 has the trademarks to both Jet2 and Jet2.com registered throughout the EU, so they cannot be held or used by anyone else.