How much are we letting go?

One of the consequences of doing a repair and part replacement with Jim Anderton (who you will know from our many videos at www.ssgm.com) is finding out how even simple, routine maintenance work can take much longer than expected. We both discovered that during our video shoot of an exhaust replacement. Normally, this kind of work should be a simple affair: remove the old system and replace with the new one. Jim and I sourced the exhaust system replacement from a major manufacturer and booked about two hours to do the job at a local independent.
Well, things did not go smoothly for us. Before we knew it, the pick-up was making things difficult for Jim and we suddenly discovered that we needed a couple of crucial parts to complete the job. Not a problem, we both thought. The shop should have the parts. When we discovered they did not, we did not panic. Like any good shop, we went down their list of parts suppliers and began calling. That's when the problems began. One dealer operation, it was a Ford part we were looking for, was going to charge us an outrageous price for what we needed. A couple of other jobbers did not have the parts we needed. After some more calls, which proved fruitless, we moved to Plan B -- driving out to some local part suppliers to see what we could find.
That's when things began to get more interesting: one place only had one of the parts we needed, and the fellow helping us left a lot to be desired. And it was not exactly the right one to boot. So we drove to another jobber, only to find they had two parts in stock, but also not exactly the right ones. Now we were stuck. Jim and I could have gone to another place, but this two-hour simple job was now taking three-hours and much more. So we purchased the two parts, went back to the first place and grabbed the other, got back to the shop and then spent an good hour modifying the three parts to fit what we needed.
In the end, the job took nearly three times a long as what it should have.
Now, here is the question that has to be asked: if Jim and I were shop owners and technicians, would we have charged for those extra hours? Ideally, we should. All that running around was necessary to fix the vehicle and get it back on the road the same day. The reality is we probably would not have, certainly not if we wanted that customer to come back to our shop. Can you imagine the reaction of the customer as you try to explain why you had to drive around for an additional two hours to source parts and you are charging them some $200 say for that 'labour?'
So, a question I'd like to ask, and I will try to find out is how much work is everyone not charging for; how much labour is simply not billed in order to keep the work and the customer?