eug hit it.
when I used to work at Ski Center in Wash DC, I could drill and mount a set of bindings in about 8 minutes, and took another 5 or so for the function check. The issue isn't how long it takes, it's how many people were there before you and want the same thing or other work done. If every job was handled under the "it only takes 15 mins" thought process, most shop employees would be working until midnight every night. Believe me, after working the weeks before and after Christmas, all a ski shop employee wants is to go hit the slopes, and definitely NOT work late for whiny customers.
On the other hand, there were times when we shop mechanics would stay 20 mins late for a customer who we knew to be honestly in a bind that wasn't of his/her own making... such customers usually rewarded us with beer or booze.