r they allowed to do that? like from the uni's perspective etc?
They can if they want, sure. If you have a valid reason... not so much. I have yet to be kicked out, however. I guess it really depends on the tutor. Some are
very laid back individuals (many are post-grad students), but others can be fairly strict (especially when you have the subject coordinator/lecturer as your tutor). Realistically, though, you're more likely to get kicked out of a lecture for talking than you are for not doing homework (because your real punishment is losing the marks, which may be the difference between a pass/fail or pass/credit and so on, and this is important when it factors into your GPA).
Some lecturers who also do tutorials are strict and hate when people don't do their homework, and can actually kick students out.
Moral of the story: If the lecturer is also your tutor, damn well do the work.