Not at all: Secondary airports are easy infrastructure to build: They don't take all that much land in the grand scheme of things, and from one of those, you can connect to 3-5 nearby hubs. Trains, on the other hand, require infrastructure to go all the way to your destination, so even if you do have a train station, it's quite possible that it's not going to take you even in the general direction of where you want to go.

Let's take, for instance, my hometown in Asturias, Spain. There's technically a train sttation... which will get someone to Madrid in about 8 hours. If someone wanted to go to Barcelona, the fastest route is still via Madrid! Going to Bilbao via the northern corridor by train is a whole 10 hours: The route is prohibitively expensive to tunnel for high speeds.

However, let's look at plane options. There's a single runway airport about an hour away with direct connections to Madrid, Barcelona, Las Palmas, Malaga, Valencia and Tenerife. Pre covid, it also had direct flights to Paris and London. The typical planes that land there aren't private jets, but just the typical narrow bodies that do short routes everywhere in the world: A319 or so.

So yes, there absolutely are plenty of cities in Europe where the train doesn't even begin to be competitive, in either price nor travel time.