Although the rules of golf are standardized, the rules that you play by depend on several factors. Some would say that everyone should play by a strict interpretation of the rules and others would allow for a looser interpretation. In my experience, it seems that the less formal the game the looser the rules. That is, the lower the stakes the less likelihood that the rules are going to be strictly adhered to. Outings with family and friends may pay little attention to the rules while leagues may want to abide by most of the rules and of course tournaments require that everyone pay strict attention to the rules. It is not that the rules are made to be broken, but for some they are just not as important in a casual setting as they would be in a formal setting. It is sometimes difficult to interpret the rules in tournaments where there are officials to help out. Having to interpret rules in a casual setting is not a fun way to spend the day.
There are surveys that indicate that over 60% of non-professional golfers do not play strictly by the rules. One such survey can be found here. Some would say that this because the rules are just too hard to interpret and that they slow the game down. There is discussion on whether or not a new set of rules should be adapted for the average or amateur (non-tournament) golfer. If a new set of rules are in order, should the USGA administer them or should it be another organization that is not connected to professional golf? I have started a discussion of this subject on Amazon.com. You can get in on the conversation here.