I appreciate a more-than-zero tolerance policy when I'm going to an unfamiliar city to play. It's good to know I won't be forfeited if I have some trouble finding the building.
If you're playing in the US, the USCF forfeit time is 1 hour.
I knew a player years ago who, when he was paired with a much lower rated player, would regularly arrive 30 minutes late. I think that he was showing his contempt for his opponent.
I think some people would arrive 30 minutes late so as to have a reason if they lose and to brag about it when they win. Like they would say, 'I arrived late but I still won anyways.' Actually I think when your opponent arrives late it is an advantage to you since you have more time to think but what is really most important is your quality as a player. If you are really stronger than your opponent, this psyche techniques doesn't work.
In the past I played in tournaments where the tolerance was 1 hour and took advantage of that fact: in one instance, before the round I was visiting the nearby city with my family and the bus back to the tournament venue was late.
However, I'm now in favor of the zero tolerance rule. After all, why chess should be an exception among other sports? What if the start of a football game would wait until one of the teams assembles on the pitch? I know, some say that it's my time and I can do whatever I please with it, but in my opinion a player should show respect to the opponent and the arbiter and be at the board when the round starts. Not to mention that a late arrival is usually noisy and distracting for the nearby boards: the late guy drops his bag on the floor, puts on his glasses, arranges the pieces, takes out his pen, starts filling the names in the scoresheet... you know the drill 
@owltuna - I'm not so sure. Some people play poorly when angry. Contempt works on those people. (I'm not advocating it though...)
Well, I mention that because of personal experience. My best OTB win was against an expert, rated over 2200 at the time, who routinely played that way, i.e. arrogantly ignoring the board and looking around the room, using body language clearly intended to express how bored he was.
My chess playing had been very sporadic, so it would be years between visits to the club. He knew I could be a strong player, but he didn't recognize me when I showed up to this tourney. I used this to my advantage and sat like a rock. A very quiet rock.
When he finally turned and starting paying attention, it was too late. I will remember that moment for a long, long time :-) I made an exchange sac that killed a knight he had posted in the center, and the position fell apart. He got a bit of counterplay late, but I ran my king across the board in an epic journey to safety, and he resigned.
Could I see that game? Sounds interesting :D
Well, I mention that because of personal experience. My best OTB win was against an expert, rated over 2200 at the time, who routinely played that way, i.e. arrogantly ignoring the board and looking around the room, using body language clearly intended to express how bored he was.
My chess playing had been very sporadic, so it would be years between visits to the club. He knew I could be a strong player, but he didn't recognize me when I showed up to this tourney. I used this to my advantage and sat like a rock. A very quiet rock.
When he finally turned and starting paying attention, it was too late. I will remember that moment for a long, long time :-) I made an exchange sac that killed a knight he had posted in the center, and the position fell apart. He got a bit of counterplay late, but I ran my king across the board in an epic journey to safety, and he resigned.
Sounds like a very gratifying game. I had something somewhat similar here. I had a won position, but only up a pawn. I did not play it the best way and it looked like I would have to settle for a draw. My opponent couldn't help himself and taunted me with "Hahahaha...now it will be a draw."
So I took a second look and noticed that, sure enough, there was a way to win the K + P ending. I replied "I believe you are talking out your arse...show me how you draw against this!" and I was so elated that I must have nearly ruptured the mouse button when I clicked "Submit Move".
Poor guy could only meekly play 2-3 more moves before resigning and concede "I guess you're right. I really thought it was a draw."
It's telling to see how club players and even experts can be so stuck up as opposed to the top players that could easily demolish them but don't make a big deal out of it.
It happens. However, some people regret doing so at zero tolerance events 
What's a 'club player' ?
What's a 'club player' ?
Is this "Stupid Answers" on Jeapordy or...
I have no problem with the zero tolerance policy for professional players but amateurs should NOT be held to the same standards as professionals imo . So, to have the zero tolerance policy for big Opens , in which many , if not most , of the players are amateurs is ridiculous . Lets not forget all the advantages professionals have ... one of the biggest ones being that most of them are paid to even play in some events ! Often their expenses are also paid ... why should an amateur like you or I be held to the same standards when we have to pay all our own expenses and the professional does not ?! I have never played in a zero tolerance policy tourney and I never will . Sometimes , being late just can't be helped ... As for uscf tournies/rules I dont think the zero tolerance policy is used and I hope it never is ....
I appreciate a more-than-zero tolerance policy when I'm going to an unfamiliar city to play. It's good to know I won't be forfeited if I have some trouble finding the building.