Bradley is correct in that the bottom line is golfer expectations (partly driven by the Augusta syndrome). It is the demand for perfect green fairways and perfect green rough that forces the costly irrigation systems and expensive mowers. Just 15 years ago, everything off the green was cut with gang mowers in a matter of minutes. Now you have to cut fairways so low that you need special fairway units that run $40K and, since they only cut a small path, you need two of them (and the operators) to be continually running. Rough units are now the same way because people don't like their rough uneven. Since they don't like it brown, they need irrigation, fertilizer and continuous cutting as well. The actual cost of each laborer is not that high, it is that you need a year round staff that is double what it used to be. I see walk mowing at municipal courses, and I still can't figure out how some private clubs are able to spend well over $1M on an 18 hole course on maintenance alone. A truly impressive ability to waste money.
Large clubhouses certainly are a factor, but only on the daily fee side. Private clubs have always had monstrous, inefficient clubhouses. But daily fee courses have gone from nothing but a pro shop to 50K foot edifices with $100K utility bills.
Sorry, golf carts have nothing to do with it. Sure, paths cost $300K, but they last 10 years, which is only $30K a year. A drop in the bucket, even if they didn't actually increase revenue (which they do).