Rob:
Your last observation is a good one.
In the old days, nothing on a golf course was really seen as a liability issue, so hitting across roads was okay ... and made the course flow a lot better than putting out, walking 75-100 yards from the green across the road to the next tee, and continuing.
An analysis of the top ten courses is particularly striking:
At Pine Valley, you hit across the driveway for the approach to the 18th hole and the tee shot at the fifth.
At Cypress Point, you tee off across 17 Mile Drive at the first.
At Pebble Beach, you hit your tee shots at 15 and 16 across residential streets.
At National, you hit the tee shot on 8 and the approach on 11 across Sebonac Road (which is pretty busy).
At Shinnecock, you hit the approach at 12 and the tee shot at 13 across a residential street.
At St. Andrews, you hit your tee shots on 1 and 18 across Granny Clark's Wynd.
There are tons of other examples of this.