In Europe roads can be very narrow and windy. You need to transport very large blades, towers, cranes which can require modification to the roads and large tracks. And large schemes can have massive transformers which are heavy and require long vehicles to transport. You might have to drive a thirty mile circuitous route avoiding weak bridges from a barge moored at a river or harbour. And whilst you could scrub out the tracks once built developers probably don't want to. It makes it easier to bring in equipment and parts if necessary. And provides easy access to the cables that will probably be run under the tracks.

There was some plan to build an airplane that could deliver parts. Probably useless in Europe but could work in less dense places.