How hard is for a complete noob to hit a golf ball off a tee? I couldn't do it at the driving range because I'd keep bending my elbows but I might just be really useless.
It depends. There are wildly varying levels of success too - from multiple airswings to making contact and it going in a forward motion. Age and exposure to sports that require similar coordination are also a factor (see Ricky Ponting as an example). If the goal is just to get it off the tee, quite a few newbies could probably at least make contact. People on here talking about them hitting a par 3 in one shot (even a short par 3, which is around 100-120m on average) are wildly optimistic though. Even with someone telling them which club to hit, the chances they'll make solid enough contact to end up on the green are slim. Then there's putting, which requires touch and an ability to read the greens. Someone new to the sport is far more likely to rack up 4 or 5 putts on a hole than they are to knock it in in 1 or 2. The pars and bogeys mentioned here are, again, wildly optimistic. Every so often someone might fluke it and do something unbelievable on a shorter hole, like make par, but I'd bet against it every single time and be way, way ahead.
To put how good pros are into perspective a little - if you understand the golf handicap system, scratch (0) is supposed to represent the handicap of someone who is good. This means they play off the stick and don't take any shots off their score at the end of the round in club competitions. To be a reasonable pro, you need to be off around +6 at your home course. This means you add 6 shots to your score at the end of a round. So if par is 72, you need to shoot 66 to play to your handicap each week. Even then, you may only be a mediocre to average player on a professional tour. A guy I played with at Tweed/Coolangatta was off +6 at our course, and played to it with relative ease. He play on the European, Web.com and PGA Tours, the latter for the last year of his career only, and while he did ok at times, he was a fair way off your Tigers, or even the Top 100 golfers in the world. He came 15th in the Sony Open one year, but that was pretty much the highlight. His issue was probably the mental side of the game, but it put him a long way off competing with the best week in week out.
While there doesn't seem to big a big physical side to golf, the hours of practice you need to do a day are tiring and if you haven't played before, you'd be pretty tired by the time you got to the 18th hole. I'm not sure how anyone could say there isn't a big mental aspect to the game either. Your swing thoughts and being able to play the game shot-by-shot have a huge influence on the end result.You need to be able to block out negative thoughts, what your fellow playing partners are doing, and forget about the last shot (especially if it was a poor one) to end up with a good result. You also need to be able to visualise what you are trying to do with each shot and have the technique to carry it off in all weather conditions. If you hit the course low on confidence, the chances are you'll have heaps.