let me try this from another direction>yet at least with driving a train there is actual scenery, and mechanisms along the route relative to the railway, I.e level crossings, signals, catenary, junctions etc.>actual scenery
flight simulators have scenery for the entire planet, even though it may not be to the level of standard as a confined route in a train simulator
also, the scenery itself is a "mechanism relative to the operation" as you can use it to identify your location, and navigate to your destination only be reference to the rendered scenery>i.e level crossings, signals, catenary, junctions.
For aviation the infrastructure is radio navigation beacons, airways, air traffic control, airports, and airspace.
Unlike in a train simulator where 'mechanism's pass you by, forcing you to notice them.. nearly everything in aviation is invisible, which causes the overwhelming majority to simply fly over/through them.
That doesn't mean they don't exist. But it does make the genre less friendly to new players.