The question is difficult in several ways. Although you're not starting with the presupposition that people tend to be lazy in academia, you describe your observations in a way that seems to support this claim. That's okay (and that's probably why you're asking the question in the first place). But consider where you are asking this. I mean, let's be honest: You didn't expect responses along the lines of
"Sure, we're all just slackers! Grab one of these cocktails with the tiny umbrellas in them, and join us! Research is far better than real work!"
Therefore, the arguments in the answers so far followed the patterns that one could expect as answers (here) to such a question:
- You don't "see" the work, and/or the results are not "tangible" - it's a different kind of "work"
- The teaching and preparation of lectures takes a lot of time
- The schedules are odd because you can do some of the "work" at any time and any place
In general: People will tend to justify what they are doing. And as a last resort, one can go down one or the other rabbit hole and start nitpicking about what constitutes "lazy", or what "work" actually means.
Fortunately, there have been some responses from people who worked in academia and in the industry. In contrast to people who went the straight "high school - college - PhD - post-doc - tenure" road, they could, at least principally, do the comparison that is at the core of the question.
I personally don't have the direct comparison, because I've mainly been working in "applied research". So the following may not really be an insightful answer, but rather a truism:
- There are workaholics who are extremely conscientious and industrious and work for 80 hours per week straight, without taking a vacation, until they achieve their personal goal.
- There are lazy slackers with the life goal of sitting in front of a PC with the monitor being arranged in a way that nobody else can see it, in an organization that is large enough so that nobody notices that they are essentially doing nothing.
And you find both sorts of people in academia and in the industry. In fact, this has been examined quite extensively: Price's law states that the square root of the number of people in an organization is doing half of the work. His work originally referred to academia and the publication count, but has also been applied to companies.
So you'd have a hard time arguing whether academia has a "lazy work culture", or more precisely: whether it has a work culture that is lazier than that in the industry. One reason for that is (not an argument for any side of the debate, but just) another observation: It's really hard to quantify academic work. When filling up shelves, standing at an assembly line, or chopping wood, for that matter, you can trivially measure and compare the amount of work that has been done. The more "abstract" the work becomes, the trickier it is to quantify it: Even in the industry, at a certain level of the organizational hierarchy, people are pushing numbers forth and back, trying to quantify the revenue that can be attributed to a manager, and at some point it's certainly impossible to break this down to the individual employee. In academia, there are very few conceivable "key performance indicators" at all. (A distressingly common one is "publication count", but we know where that one leads...). There are few people in the world who could dare to "quantify" what a certain researcher has achieved, let alone make a profound statement about how much time would have been "appropriate" for that achievement.
(So, subjectively, I wouldn't say that academia has a "lazy work culture" per se. But I'd tend to say: For someone who is lazy, academia makes it far easier to get away with it - particularly when the person has tenure. Strongly related: What happens to unproductive professors? )