Sounds like that inspector's schedule is built on hopes and prayers instead of actual appointments. Three times in one week isn't just bad luck, it's a sign they're completely overbooked or just terrible at their job. Your buddy should demand a different inspector from the company, because this one clearly can't manage a calendar. At that point, the cancellations cost more than just time, they tank the whole project's flow. I'd be calling the main office to complain, not just taking it.
Remember that inspectors often juggle too many jobs at once. They get called to emergency sites that mess up their whole day. This means our planned inspections get bumped through no real fault of their own. Try calling the office early to confirm the day before, not just booking and hoping. That way you can catch a reschedule before it wrecks your schedule. It's a broken system, but working around it beats just getting mad.