In addition: Not all airports have radar and even if they have, they might not be able to give you radar vectors. This can depend on the number of ATC controllers at the airport and density of traffic, the quality of the radar, the qualification of the ATC controllers, etc etc.
In the "old days," when there were no such thing as STARs or radars, all aircraft had to fly "full procedures", which normally meant flying overhead the airport or a nearby navigational beacon, flying
away from the airport for a pre-determined period of time, or to a certain distance from the airport while descending, and then turning back and getting established on the inbound track before commencing further descent on the inbound track.
The STARS were originally designed for the benifit of the pilots (and in the end for the passengers!) so that they wouldn't have to fly these ineffective and time-consuming procedures to get lined up with the final approach track.
I am not too familiar with the FAA rules (flying in JAA-area myself), but certainly if you don't want, or if you are unable, to fly the STAR, you would have to fly this lenghty full procedure. -Unless, of course, the ATC controller is able, and gives you radar vectors.
But Manflex55 has a point, though: On many of the airports that I fly in to, we would rather request a different track than the STARS to avoid turbulence over mountainous terrain, if there are strong winds from a certain direction.
And if we don't get it, and the winds are strong enough - It's time for the magic Mayday call.
This has never happened, though, and as you probably understand, LETS FLY, getting an aircraft down on the ground is a matter of careful cooperation between the pilots and the ATC controllers.
Nick.