Not always in Europe. On some routes Lufthansa and Austrian allow booking of bus or rail transfers to the hub as a leg on the air ticket, which also means they

Not always in Europe. On some routes Lufthansa and Austrian allow booking of bus or rail transfers to the hub as a leg on the air ticket, which also means they guarantee the connection even in the case of delays. Examples: "Lufthansa Express Bus" which used Deutsche Postbus routes between Salzburg and Munich (now sadly defunct since Flixbus took over the route), and Austrian Airlines selling tickets on OeBB trains between Salzburg and Vienna (though personally I'd still prefer the 40min flight over a 2.5h train in that case). I always found it particularly amusing, while riding the SZG-MUC bus route, that a lonely little bus stop on the edge of Rosenheim, Bavaria has its own IATA airport code (ZPR).