Can builders plan?

Let me start by saying that I believe my builder is quite good. He has integrity and responds well to requests related to my dissatisfaction.

Further, my builder signed a fixed price contract with a penalty clause for late delivery. Unusual, I believe.

But: I have only now taken occupancy of my transformed townhouse - one month after the three month deadline. Further, the builder used crap subcontractors for the cupboards and ceilings, resulting in them being fired and the work redone (not an insubstantial contribution to the delay). And now, after yesterday's monsoon in Johannesburg, the veranda ceiling is ruined after the roof above leaked (attention to which had been drawn after the first signs of leaks after much softer rains).

So my question is this: why do even good builders take shortcuts / try to save money to increase their profits? Don't they notice that it always results in redoing work at great expense?

I think I must become a builder. Jeez. If I was even remotely good (read: reliable, timely, to specification, right-first-time), I'd make a bundle. Why has the market not realized this? I would have thought that there is a clear signal to potential good builders, with all those out of work in a booming economy (and booming building trade - my builder struggled to get bricks due to the amount of building going on).

I guess part of the problem is customers who try to bargain prices down - if you pay twice as much, do you have no problems? Considering what I paid, I hope not...