Yes, it's very typical, and there are quite a few factors that resulted in the system evolving to end up being the way it is.
The first factor is that many PhD students are little use in research. They are highly inexperienced and low-efficient, often have difficulties organizing themselves to do complex tasks, have no idea how to write research articles, and absorb a lot of time and effort of their mentors. On top of that, if we are talking about non-English-speaking countries, almost all local students don't have the skills to express their research findings in English in a way the editors of top journals would be happy with. Some PhD students become real pain for their mentors, and you never know in advance whether a particular student will be a problem or not. And you generally can't trust research results obtained by a PhD student, because an error may be everywhere, so you have to verify in one or another way. I remember a professor saying, "I'd rather spend my grant funds to hire an experienced postdoc than three PhD students." In view of their low value, it well may be that PhD students are actually overpaid rather than underpaid! Now that PhD stipends are fixed and can't be negotiated between professors and students, what's left to compensate for the low efficiency is working hours.
The second factor is that accepting a PhD student position is the easy way for graduates. You know, you graduate from a university, and you have done some research for your Master diploma and have some connections with some professors. One of them is offering you a PhD position, and all you have to do to secure a white-collar job for yourself for the next few years is to simply say yes to his offer. You don't need to acquire new skills to get that job, and you don't need to send out your CV to hundreds of companies. And you don't need to pass numerous interviews and adapt to a new kind of working environment. You aren't afraid to get fired quickly and be left without any money to pay your bills and rent an accommodation. But everything in this world has a price - and you have to pay for the easiness of this way by earning less money and/or working longer hours.
And I guess there is a third factor, albeit it's debatable. There are many university graduates in relatively poor countries who want to migrate to the West. They consider a PhD student position at a Western university as a stepping stone and are happy to work in this stage just for food and a shared room. A Western professor gets a highly motivated hard-working student graduated from, let's say, one of the top universities in China or India and pays him very little money from a grant, and the student gets an excellent opportunity to get a Western degree and build a career in the West. It's a win-win situation, so why would scientists be motivated to change that? And here comes the expectation of long working hours: Otherwise why would a professor hire you, a local, if he can instead hire someone from abroad who will happily work hard 10 hours a day, 6 days a week, for the same stipend?
Also, only a small part of PhD students can get a tenure position later in their lives, for there are too few tenure positions available. It's a kind of bottleneck, and this is pretty unhealthy for science and results in a fierce competition and the publish-or-perish attitude. Many early-career researchers get obsessed with publishing as many articles as possible, no matter the quality and actual significance. Some young scientists even conspire to mutually include each other as co-authors to their papers. The old good spirit of science is getting lost, and nowadays it's about the number of publications and the h-factor, to a considerable degree. So what can be done about that, if increasing the number of tenure positions is out of question? Demotivate prospective PhD students by low pay and long working hours in order to ensure that only those who truly love science enter the game. And those students will be happy to do research 60 hours a week, because that's what they are passionate about.
I'm afraid it's hard to change the system without addressing the factors listed above.
I humbly hope that my answer helps look at the issue from a somewhat different perspective as compared to what is offered in other answers.