Polaris, I have to take issue- in part- with your characterization.
Southwest could never have existed in the US, in its present form, before airline deregulation; the only way that they were able to start up when they did was that they flew (at that time) only within the state of Texas, and thus fell outside the route authority of the now-defunct CAB (Civil Aeronautics Board). Flights between different states were doled out by the government, with only limited number of airlines allowed to serve each pair.
It was only after airline deregulation that WN was able to serve interstate markets and (with the unique incubator of the state of Texas, outside federal jurisdiction, but large enough to support growing air traffic) Southwest was by that time large enough, with a well-proven enough operating concept, that they were able to expand with great success.
Southwest succeeds because it has high standards- where it matters. Having traveled all over the country, and some internationally, I can tell you that the standard of service which Southwest provides- service that matters- is one rarely matched by any carrier, at any price. They are reliable, have safety standards which are the highest, and they treat their passengers with respect. Southwest has grown on the repeat business of business travelers who revel in the high-frequency and reliable performance WN provides; not the cheap-fare "backpacker" traveler.
The European ailrline market is now seeing some of the same effects, but (as noted above) much of the role filled by WN here (especially in its earlier days) is well-filled by Europe's exceptional rail infrastructure.
To suggest that WN's success stems from a "lowering" of standards is silly; very few business travelers I know (the ones who cherish getting home to the family) would choose to fly a "full-service" airline, if Southwest could get them home sooner, with greater certainty, and at a less-confiscatory fare.
...three miles from BRONS, clear for the ILS one five approach...