Money and people that actually golf in real life
The shocking thing is that their lead developer (Shaun) is a single digit handicapper IRL. In one single post he said that he played XX number of rounds per year and is a single handicapper and that they strived for the having the most realistic physics engine of any golf game... and they think they've achieved that.
Yet, you can take a sandwedge, deloft it and hit a beautiful high arching 200 yard shot as if you just nutted a good 4 iron right down the pipe. And chips randomly check up like the landed on sticky paper.
How a real golfer could develop a golf game with issues like this and claim that they have the most realistic physics engine of any golf game is just baffling to me.
Now that's not to say that it's ALL bad. To me, the game plays quite well but I have to enforce my own house rules (no use of loft, and shot feedback turned off) and I'll likely never get any real competitive play because 99% of that community use the dial-a-distance loft mechanism like it's a drug.