That is most likely because the BW users are set up as SERVICE type users and are not subject to password validity parameters.
The ERP users are DIALOG type users and the compliance to current policy parameter is applicable for them.
-> Several of the login* parameters have user type dependencies.
But there is also another possible reason. Is your BW system on 7.31 basis release? Go to transaction SECPOL and check whether there are any available policies there... do any of them contain the compliance setting = 0 and are assigned to the users?
-> Policies take preference over parameters now.
Cheers,
Julius