Compare it to Europe though.
For shorthaul flights, you're looking at one of several airlines.
Ryanair and easyJet dominate the budget airline sector, with additional competitors in the form of Wizz Air, Norwegian Air Shuttle and FlyBe depending on your location.
Once you start opening it up to Flag Carriers, you have a huge variety of airlines, some operating a budget model, some not, plus those budget airlines which are focussed on certain countries, like Eurowings, Lauda Air, Iberia Express, Aer Lingus, Joon, Hop!, Transavia, Vueling, Air Europa, airBaltic and so on (there are too many to mention).
Going from London Heathrow to Franfurt (am Main), you'll have a selection of several flag carriers. Direct, you'll just have British Airways and Lufthansa, but take a connecting flight, and it opens up several more airlines. Leave from Gatwick and your options change again, and from Stanstead, Luton or Southend, your options are still really diverse.
Don't start with transcontinental flights, because the sheer number of options from both European Flag Carriers for direct flights, or through a hub in Europe is joined by budget airlines, as well as the US, Middle Eastern and Asian carriers.