This is a trap almost everyone can fall into when dealing with someone with autism, especially high functioning autism. Things can appear so "normal" that it's easy to forget that we're dealing with someone with a handicap.
Nathan suffers more from this than Alex does. His ability to cope with change is phenomenal but he can still get overwhelmed faster than a typical child would. He's having a hard time right now with the transition between school routine and summer routine, not to mention the holiday disruption of Canada Day. It would be easy to get frustrated with him and assume he's misbehaving rather than dealing with something at the brink of his tolerance. (To my shame and regret, I don't always make the right call when deciding which it is.)
Like so many effortless things, setting Nathan up to succeed takes a great deal of behind the scenes work. We use social stories, we give him verbal and visual schedules, we give him space to express his emotions and most of all, we try to be consistent. When we say something is going to happen, we have to keep our word.
A friend of mine whose son also has high functioning autism was telling me about her frustrating discussions with a caregiver who doesn't quite understand the importance of predictability and reliability. Her son doesn't like having to leave the house. He likes having the comfort and security of his things around him.
My friend has been working on getting him to be comfortable going out on limited errands. He expressed some jealousy about his sister getting to pick up some trinkets from the dollar store, so she used it as a motivator: you can go out to the dollar store and pick up something for yourself.
The caregiver took the kids out and returned much later than expected. Her son was in complete meltdown, frustrated to the point of screaming. My friend was somewhat at a loss until she discovered that the caregiver had spontaneously added another store to the outing.
This may not seem huge on the surface but to her son, it was more than he could handle. My friend is furious, knowing that weeks of work may be down the drain. Why should he want to go out again when his trust has been violated in this way?
Most kids might be tired and cranky after being dragged to an extra stop on an outing. But they wouldn't be devastated by the change and they would have the verbal and social skills to be able to express their feelings.
Imagine being trapped in a foreign country with only the rudiments of a language. You've learned how to get your basic wants by trial and error without really understanding how things work. You have a system which works but is incapable of adapting to change. And suddenly there's a massive change. Any of us would feel overwhelmed and frustrated in that circumstance and we'd be completely unable to express that frustration or figure out a way to get things back to the way they worked before.
Remembering the inherent alienness of ordinary life to someone with autism can help us to understand a tantrum not as the whining of an entitled brat but as an expression of terror from a lost child.