IT'S NOT.
Pictures cannot tell a 1000 words when it comes to elevations, lies in the rough, putting breaks etc...
imo, it would take at least a month to map anything remotely good, 2 if you want the details of the course in the correct place, 3 if you want it to play relatively like real life, and even longer if you want the course to be truly realistic.
WGT only has 4 courses but it's not for the lack of trying to add more in the game, it just takes plenty of mapping and other shizam to make the courses play like they do in real life. I'm sure if WGT's staff didn't value quality over quantity we could have 10 courses by now but they'd all look like they came straight off google earth with no attention paid to the little dips and twists on the fairway and somewhat inaccurate greens.