I was a science major, and this is standard fare for a lab class (at least in my experience). If this was a 300 person lecture class, then I would say that’s pretty strict but not necessarily outrageous. But for a lab class, I’m not at all surprised.
My department also had a rule that if you missed the first class you were dropped, and the drop deadlines were also different for lab courses (you had until the second class, I think, to drop without a W, rather than until the end of the fourth week of classes like you did for every other course). Lab classes are often in high demand. Different majors may require the class, but space is often severely limited because you need more space and equipment to accommodate a small number of students in a lab class. It’s not quite the same as cramming hundreds of students in a lecture hall. You need a lot of materials and space for lab classes, and as such, they can’t afford to have students who can’t manage to show up to class on time when there are lots of students on the waitlist who would jump at the chance to be on the class so they can graduate on time. It’s often a premium spot, and they want to make sure it’s put to good use.
Also, regarding the amount of absences allowed, I think it’s pretty generous to allow one free, no-questions-asked absence. That’s huge in a lab class. In labs, you can’t really make up the work (or it’s very difficult to do). If you miss part of the lab, that’s it. You often can’t do that part because you only get so much time in the lab. You have to move on to the next part of the lab or you will be behind forever. It’s not like other more “typical” lecture courses where you can borrow notes or read the textbook or go over slides and catch up what you missed on your own. At least at my school, if you missed a day, you missed that part of the lab (often forever with no chance to do it), and it was a huge headache trying to figure out what you were going to do about it. Experiments could often last multiple days, so if you missed one day of class, then your entire experiment was a goner. It’s a big deal to miss a lab class. Don’t miss one.
As for unexpected things, like a funeral or a serious illness or a car accident–for most students, these won’t be an issue and they will be able to make any class. The one allowed absence is for the random time you had transportation issues or was sick or whatever. I would argue that for the vast majority of students that will be more than enough. For students who do have really unfortunate situations where they have to miss class, they will likely be able to discuss this with the professor and come up with a plan. The plan may be to take an incomplete or to take a medical withdrawal or some other solution. The no “exceptions” is likely to ward off students trying to come to the professor after the fact saying I was sick and in bed or I had this other situation that I wasn’t able to talk to you about until after the fact (that may or may not be true). True situations that require missing more than one class will of course happen to some students (like being hospitalized or having an immediate family member pass away) and you can still work it out with your professor. The answer might be having to withdraw from the course or there might be a way to resolve the issue. But it’s really difficult–if you can’t be in the class for multiple days, then you will miss a lot of the work. And you’re often graded on your lab work, as well as your knowledge of the material. So as unfortunate as your situation might be, there’s not a lot they can do about it if you can’t be there.
I’ve had friends who have had unexpected medical emergencies that resulted in hospitalizations, doctor-ordered bed rest, or an inability to go to class. They all took incompletes or withdrew for medical reasons in courses that they couldn’t otherwise finish. I’ve had family members pass away while I was in school, and each time, I missed one day of class (even though I was flying 2500 miles away) because I had to be in class. It happens, but you can’t exactly build your entire course policy around every student having serious or multiple unexpected emergencies every term. Especially in a class where it’s really hard to make-up absences. I get that things happen, but for most students, they should be able to get to class.