Anecdotally, in European universities, bachelors are the "get in as many people as we can for the tuition fees", while masters are the "let's be as selective as we can get away with".
Sometimes it's even worse... For example, in France, a university is required by law not to be selective for it's first year programs, as long as the candidate graduated high school.
I assume there's an upper limit on the number of students an university can take in for the first year, determined by staff and classroom availability.