Assume an average rate of €10/hour, with a working week of 37.5 hours, that gives you an income of €375.
If you're working 7.5 hours a day, you're on-call for 16.5 hours Mon-Fri, and 24 hours for Sat/Sun. That gives a total of (( 16.55 + 48 ) 10) = €1350.
So yes, you get paid a lot. (Of course the hourly salary there was low to simplify the numbers, but you can see the income for working a week on-call is about the same as working three normal weeks.)
