I don't think Southwest would be too happy with the Ryanair comparison!
There have been a number of stories in the UK press about how Ryanair treat delayed passengers (badly), wheelchair passengers (they charge for wheelchair use), optimistic descriptions of the airports they use (Hamburg instead of Lubeck, Brussels instead of Charleroi, Paris instead of Beauvais etc etc), virtual impossibility of getting the promotional fares you want at the times you want to travel (you normally have to avoid Mondays, Fridays and Sundays and then play around with an unhelpful website to get anywhere near the headline fares they quote).
Ozstamps: Taxes and passenger service charges are a whole different topic. At present they are relatively easy to understand, if unpopular. But they are just about to be changed to something a lot more complicated.
UK Airline passenger duty (Ignoring domestic UK flights for simplicity) - N.B. This is not an airport tax! - the money goes to the UK Treasury - airport charges are extra.
Now
Flights to EU airports: £10
Flights to non-EU airports: £20
Note that Zurich is £20 (non-EU) but Geneva and Basel are £10 (airports are on French territory). Logical? No.
from April
flights to EU airports: £5 economy and single class cabins; £10 premium
flights to non-EU airports: £20 economy and single class cabins; £40 premium, i.e. premium economy, business and first
To this must be added UK passenger service charges (different for each airport, but say around £6-7 - these used to be included in the fare, but are now added and shown separately on the ticket) as well as any arrival charges at the destination airport plus any tax and charges on the return journey.
Sorry to go on. It used to be simpler.
Some airlines do not charge p.s.c.'s. At present, a BA 'free' flight to Zurich costs around £34 in tax and charges. An AA 'free' flight on BA costs £20, i.e. they don't charge the p.s.c.'s - at least they didn't the last time I did it. I suppose this will stay the same in April, though Geneva and Basel will be £5 less than now. This will mean the APD on a flight to Zurich will be 400% of the cost to Geneva or Basel! Logic? None.
If Concorde re-emerges, the APD will be £20 (single cabin) while Virgin's Premium Economy and BA's World Traveller Plus will incur APD of £40.
Logical? No. It's just a money-spinner for the UK Government.