I'm a lecturer. Not on strike this term but I have been in the past - over pensions and working conditions.
We hate going on strike. We hate that it affects the students; we want to be teaching them. But it's the only lever we have to pull when our employers won't listen or make meaningful attempts to address demands. We are also withdrawing our labour from research but ultimately because the university makes more money from students, it's withdrawing from teaching that hurts our employers more. It's the same for passengers affected by rail strikes, patients affected by doctors strikes, schoolchildren affected by teachers' strikes.
Universities care about league tables and the National Student Survey. Poor performance one year affects recruitment in the next, and so future cash flow: universities want happy students, who are getting the full teaching experience. Threats to student experience can bring management back to the table, especially if students are largely supportive of their lecturers for choosing to take action, if frustrated at missing teaching.
I also think I am showing my students that they can respond and can have a voice, via collective action, when their employer behaves unreasonably. Striking undoubtedly reversed planned cuts to my pension, which is worth tens of thousands in my retirement.
It's actually quite difficult to organise a strike: you have to have a large union turnout in the ballot, then a majority saying yes, you have to select the dates in advance (and balance support among workers vs the pay they lose).
Your daughter won't get any compensation as long as she meets the learning objectives for the courses she's taking. If she doesn't do that, she might have a case. Contact the Office for Students.