I am wondering if it would be difficult to get back to a normal job
working a set amount of hours every day, in the same place. is that
why most people stay in academia after getting a phd?
Forgive me if I'm wrong, but it looks like the question you're really asking is if you will be able to find a workplace with the same schedule [lack of], or if not, if you'll be able to adjust. The only advice here is: try it. Get a job, in academia or not, and see how you handle it.
From what I've seen, this kind of organization is definitely not the norm even in the academic world, since once you start collaborating with people, they will expect to be able to see you at office hours without having to set a meeting weeks in advance. (For what it's worth, it's not even that common for PhD students in my experience).
However, this does not mean that you will not be able to find a boss who allows you to have your own schedule - though in the "normal life" (amazing choice of words in your title!), working in coffee shops or spontaneously taking a day off because you're tired may be pushing a bit too far. The point is, every workplace is different, every boss is different: some people will trust you and only care about results and allow you to set your own schedule, some will be controlling freaks and check if everyone arrived on time. Depending on the field, some companies have policies for working remotely if the kind of work you do allows it. Don't hesitate to ask about the schedule and flexibility if you're offered a position, it's definitely one of the points to consider - and obviously an important one for you.
Basically, you will have to find a job, either in academia or not, and see if you can handle their rules. If you can't, look for a more flexible one, and repeat the process. If you still really can't handle any of it, you may need a longer job search to find the perfect place where no-one will care. Personally, I noticed that the more interesting the job is, the less I care about having to be there way earlier than I'd chose to. And a lot of places offer flexible time, which is a good compromise even if it still means you have to come five days a week... all in all, you should be okay. Good luck!