Tarmach,
The scenario you describe suggests that thay don't get enough applicants with the 4 year degree. Some do get hired without the degree, however, there are lots of applicants fighting for jobs at the Majors. Contrary to speculation there are not enough jobs at the majors for everybody and if a 4 year degree is what they want, then you jump through the hoops.
Having said that, when times get tight they will drop the requirement and hire those without.
I do believe they accept the UK equivalent of the degree program ie 3 years.
Regards
FYF