How do golfers define "the tee area"? According to Google Earth the flat area of grass where you can put a tee is 38 metres long and the Sun implies that golfers in the masters would take the tee shot from the back of that area. On the assumption that Rahm took the shot from the front edge of that area (which is what I would do if I was looking to skim the lake), he was more than 30 metres in front of the official tee.
I don't think golfers define it at all. The tee area is defined by the course and trounament officials, not the golfers. And the tee area is often pretty large, as is the case here.
However tournament rules may define a smaller areas for particular types of tournament. So, for example elite professional men may tee off from an area at the back of the overall tee area, while elite women may use a part nearer the pin, thereby reducing the effective length of the hole. Amateurs likewise may be able to use the front of the tee area.
So it is unlikely that Rahm would have been able to tee off from where he did in the actual tournament, but I don't think that detracts from the shot as the issue isn't really the length of the shot but the skill involved in pulling it off.
